Fixes https://github.com/flutter/flutter/issues/142286

This is a refactor. No code behavior changes should be observed.

Reland of https://github.com/flutter/flutter/pull/132985. Fixes the path to AssetManifest.bin in flavors_test_ios

Reverts flutter/flutter#132985
Initiated by: christopherfujino
This change reverts the following previous change:
Original Description:
Provides support for conditional bundling of assets through the existing `--flavor` option for `flutter build` and `flutter run`. Closes https://github.com/flutter/flutter/issues/21682. Resolves https://github.com/flutter/flutter/issues/136092

## Change
Within the `assets` section pubspec.yaml, the user can now specify one or more `flavors` that an asset belongs to. Consider this example:

```yaml
# pubspec.yaml
flutter:
  assets:
    - assets/normal-asset.png
    - path: assets/vanilla/ice-cream.png
      flavors: 
        - vanilla
    - path: assets/strawberry/ice-cream.png
      flavors:
        - strawberry
```

With this pubspec,
* `flutter run --flavor vanilla` will not include `assets/strawberry/ice-cream.png` in the build output.
* `flutter run --flavor strawberry` will not include `assets/vanilla/ice-cream.png`.
* `flutter run` will only include `assets/normal-asset.png`.

## Open questions

* Should this be supported for all platforms, or should this change be limited to ones with documented `--flavor` support (Android, iOS, and (implicitly) MacOS)? This PR currently only enables this feature for officially supported platforms.

## Design thoughts, what this PR does not do, etc.

### This does not provide an automatic mapping/resolution of asset keys/paths to others based on flavor at runtime.

The implementation in this PR represents a simplest approach. Notably, it does not give Flutter the ability to dynamically choose an asset based on flavor using a single asset key. For example, one can't use `Image.asset('config.json')` to dynamically choose between different "flavors" of `config.json` (such as `dev-flavor/config.json` or `prod-flavor/config.json`). However, a user could always implement such a mechanism in their project or in a library by examining the flavor at runtime.

### When multiple entries affect the same file and 1) at least one of these entries have a `flavors` list provided and 2) these lists are not equivalent, we always consider the manifest to be ambiguous and will throw a `ToolExit`. 

<details>
For example, these manifests would all be considered ambiguous:

```yaml
assets:
  - assets/
  - path: assets/vanilla.png
    flavors: 
      - vanilla

assets:
  - path: assets/vanilla/
    flavors: 
      - vanilla
  - path: assets/vanilla/cherry.png
     flavor:
      - cherry

# Thinking towards the future where we might add glob/regex support and more conditions other than flavor:
assets:
  - path: assets/vanilla/**
    flavors:
      - vanilla
  - path: assets/**/ios/**
    platforms: 
       - ios

# Ambiguous in the case of assets like "assets/vanilla/ios/icon.svg" since we 
# don't know if flavor `vanilla` and platform `ios` should be combined using or-logic or and-logic.
```

See [this review comment thread](https://github.com/flutter/flutter/pull/132985#discussion_r1381909942) for the full story on how I arrived at this decision.
</details>

### This does not support Android's multidimensional flavors feature (in an intuitive way)

<details>

Conder this excerpt from a Flutter project's android/app/build.gradle file:

```groovy
android {
    // ...

    flavorDimensions "mode", "api"

    productFlavors {
        free {
            dimension "mode"
            applicationIdSuffix ".free"
        }

        premium {
            dimension "mode"
            applicationIdSuffix ".premium"
        }

        minApi23 {
            dimension "api"
            versionNameSuffix "-minApi23"
        }

        minApi21 {
            dimension "api"
            versionNameSuffix "-minApi21"
        }
    }
}
```

In this setup, the following values are valid `--flavor` are valid `freeMinApi21`, `freeMinApi23`, `premiumMinApi21`, and `premiumMinApi23`. We call these values "flavor combinations". Consider the following from the Android documentation[^1]:

> In addition to the source set directories you can create for each individual product flavor and build variant, you can also create source set directories for each combination of product flavors. For example, you can create and add Java sources to the src/demoMinApi24/java/ directory, and Gradle uses those sources only when building a variant that combines those two product flavors.
> 
> Source sets you create for product flavor combinations have a higher priority than source sets that belong to each individual product flavor. To learn more about source sets and how Gradle merges resources, read the section about how to [create source sets](https://developer.android.com/build/build-variants#sourcesets).

This feature will not behave in this way. If a user utilizes this feature and also Android's multidimensional flavors feature, they will have to list out all flavor combinations that contain the flavor they want to limit an asset to:

```yaml
assets:
  - assets/free/
    flavors:
      - freeMinApi21
      - freeMinApi23
```

This is mostly due to a technical limitation in the hot-reload feature of `flutter run`. During a hot reload, the tool will try to update the asset bundle on the device, but the tool does not know the flavors contained within the flavor combination (that the user passes to `--flavor`). Gradle is the source of truth of what flavors were involved in the build, and `flutter run` currently does not access to that information since it's an implementation detail of the build process. We could bubble up this information, but it would require a nontrivial amount of engineering work, and it's unclear how desired this functionality is. It might not be worth implementing.

</details>

See https://flutter.dev/go/flavor-specific-assets for the (outdated) design document. 

<summary>Pre-launch Checklist</summary>

</details>

[^1]: https://developer.android.com/build/build-variants#flavor-dimensions

Provides support for conditional bundling of assets through the existing `--flavor` option for `flutter build` and `flutter run`. Closes https://github.com/flutter/flutter/issues/21682. Resolves https://github.com/flutter/flutter/issues/136092

## Change
Within the `assets` section pubspec.yaml, the user can now specify one or more `flavors` that an asset belongs to. Consider this example:

```yaml
# pubspec.yaml
flutter:
  assets:
    - assets/normal-asset.png
    - path: assets/vanilla/ice-cream.png
      flavors: 
        - vanilla
    - path: assets/strawberry/ice-cream.png
      flavors:
        - strawberry
```

With this pubspec,
* `flutter run --flavor vanilla` will not include `assets/strawberry/ice-cream.png` in the build output.
* `flutter run --flavor strawberry` will not include `assets/vanilla/ice-cream.png`.
* `flutter run` will only include `assets/normal-asset.png`.

## Open questions

* Should this be supported for all platforms, or should this change be limited to ones with documented `--flavor` support (Android, iOS, and (implicitly) MacOS)? This PR currently only enables this feature for officially supported platforms.

## Design thoughts, what this PR does not do, etc.

### This does not provide an automatic mapping/resolution of asset keys/paths to others based on flavor at runtime.

The implementation in this PR represents a simplest approach. Notably, it does not give Flutter the ability to dynamically choose an asset based on flavor using a single asset key. For example, one can't use `Image.asset('config.json')` to dynamically choose between different "flavors" of `config.json` (such as `dev-flavor/config.json` or `prod-flavor/config.json`). However, a user could always implement such a mechanism in their project or in a library by examining the flavor at runtime.

### When multiple entries affect the same file and 1) at least one of these entries have a `flavors` list provided and 2) these lists are not equivalent, we always consider the manifest to be ambiguous and will throw a `ToolExit`. 

<details>
For example, these manifests would all be considered ambiguous:

```yaml
assets:
  - assets/
  - path: assets/vanilla.png
    flavors: 
      - vanilla

assets:
  - path: assets/vanilla/
    flavors: 
      - vanilla
  - path: assets/vanilla/cherry.png
     flavor:
      - cherry

# Thinking towards the future where we might add glob/regex support and more conditions other than flavor:
assets:
  - path: assets/vanilla/**
    flavors:
      - vanilla
  - path: assets/**/ios/**
    platforms: 
       - ios

# Ambiguous in the case of assets like "assets/vanilla/ios/icon.svg" since we 
# don't know if flavor `vanilla` and platform `ios` should be combined using or-logic or and-logic.
```

See [this review comment thread](https://github.com/flutter/flutter/pull/132985#discussion_r1381909942) for the full story on how I arrived at this decision.
</details>

### This does not support Android's multidimensional flavors feature (in an intuitive way)

<details>

Conder this excerpt from a Flutter project's android/app/build.gradle file:

```groovy
android {
    // ...

    flavorDimensions "mode", "api"

    productFlavors {
        free {
            dimension "mode"
            applicationIdSuffix ".free"
        }

        premium {
            dimension "mode"
            applicationIdSuffix ".premium"
        }

        minApi23 {
            dimension "api"
            versionNameSuffix "-minApi23"
        }

        minApi21 {
            dimension "api"
            versionNameSuffix "-minApi21"
        }
    }
}
```

In this setup, the following values are valid `--flavor` are valid `freeMinApi21`, `freeMinApi23`, `premiumMinApi21`, and `premiumMinApi23`. We call these values "flavor combinations". Consider the following from the Android documentation[^1]:

> In addition to the source set directories you can create for each individual product flavor and build variant, you can also create source set directories for each combination of product flavors. For example, you can create and add Java sources to the src/demoMinApi24/java/ directory, and Gradle uses those sources only when building a variant that combines those two product flavors.
> 
> Source sets you create for product flavor combinations have a higher priority than source sets that belong to each individual product flavor. To learn more about source sets and how Gradle merges resources, read the section about how to [create source sets](https://developer.android.com/build/build-variants#sourcesets).

This feature will not behave in this way. If a user utilizes this feature and also Android's multidimensional flavors feature, they will have to list out all flavor combinations that contain the flavor they want to limit an asset to:

```yaml
assets:
  - assets/free/
    flavors:
      - freeMinApi21
      - freeMinApi23
```

This is mostly due to a technical limitation in the hot-reload feature of `flutter run`. During a hot reload, the tool will try to update the asset bundle on the device, but the tool does not know the flavors contained within the flavor combination (that the user passes to `--flavor`). Gradle is the source of truth of what flavors were involved in the build, and `flutter run` currently does not access to that information since it's an implementation detail of the build process. We could bubble up this information, but it would require a nontrivial amount of engineering work, and it's unclear how desired this functionality is. It might not be worth implementing.

</details>

See https://flutter.dev/go/flavor-specific-assets for the (outdated) design document. 

<summary>Pre-launch Checklist</summary>

</details>

[^1]: https://developer.android.com/build/build-variants#flavor-dimensions

Fix tool exit message shown when user provides a non-list to "assets" for a deferred component (#137837)

Fixes #136163

Remove 1745 decorative breaks

* dart fix --apply

* manual fixes

* fix after merge conflicts

* review

This adds avoid_dynamic_calls to the list of lints, and fixes all instances where it was violated.

Importantly, this lint is NOT turned on for flutter/packages/test, because those changes are happening in another PR: #84478

* Revert "Enable dart_plugin_registry_test (#76645)"

This reverts commit 109e0bb9.

* Revert "Apply changes caused by https://github.com/flutter/flutter/pull/76662 (#77093)"

This reverts commit cdca6485.

* Revert "Disable clang format in the plugin registrants (#76662)"

This reverts commit dadbd47d.

* Revert "Disable warnings for the dart plugin registrant (#76561)"

This reverts commit 098ece52.

* Revert "Remove dart_plugin_registry_test timeouts (#76838)"

This reverts commit 1610a274.

* Revert "Implement dartPluginClass support for plugins (#74469)"

This reverts commit b7d48062.

Kick.

flutter_tool: DeferredComponent and LoadingUnit classes, Manifest deferred-components parsing (#75394)

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

[flutter_tools] allow applications to specify additional license files to be bundled into the application NOTICES automatically (#73430)

[flutter_tools] Display "no platforms" message based on results when creating plugins project (#70215)

* Add punctuation for unterminated sentences in doc comments

* Addressing review nit

Allow configuring the flutter_manifest to support a synthetic package, this is done through flutter: generate: true.

When running pub get, insert a flutter_gen entry into the packages if it does not already exist. This points to .dart_tool/flutter_gen, which can be updated to contain the generated intl sources (But doesn't currently)

Adds an integration test that verifies this code can be run and imported when enabled.

Part of #60914

[flutter_tools] Handle special characters during conversion of asset manifest paths into URIs (#48829)

* Update project.pbxproj files to say Flutter rather than Chromium

Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.

* Update the copyright notice checker to require a standard notice on all files

* Update copyrights on Dart files. (This was a mechanical commit.)

* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.

Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).

* Clean up the copyrights in non-Dart files. (Manual edits.)

Also, make sure templates don't have copyrights.

* Fix some more ORGANIZATIONNAMEs

* On flutter tool crash suggest GitHub template

* Shorten GitHub URLs

* Whitespace

* Wording tweak from @InMatrix

* Review edits