`flutter build aar`

This new build command works just like `flutter build apk` or `flutter build appbundle`, but for plugin and module projects.

This PR also refactors how plugins are included in app or module projects. By building the plugins as AARs, the Android Gradle plugin is able to use Jetifier to translate support libraries into AndroidX libraries for all the plugin's native code. Thus, reducing the error rate when using AndroidX in apps.

This change also allows to build modules as AARs, so developers can take these artifacts and distribute them along with the native host app without the need of the Flutter tool. This is a requirement for add to app.

`flutter build aar` generates POM artifacts (XML files) which contain metadata about the native dependencies used by the plugin. This allows Gradle to resolve dependencies at the app level. The result of this new build command is a single build/outputs/repo, the local repository that contains all the generated AARs and POM files.

In a Flutter app project, this local repo is used by the Flutter Gradle plugin to resolve the plugin dependencies. In add to app case, the developer needs to configure the local repo and the dependency manually in `build.gradle`:


repositories {
    maven {
        url "<path-to-flutter-module>build/host/outputs/repo"
    }
}

dependencies {
    implementation("<package-name>:flutter_<build-mode>:1.0@aar") {
       transitive = true
    }
}

This reverts commit 11460b83.

`flutter build aar`

This new build command works just like `flutter build apk` or `flutter build appbundle`, but for plugin and module projects.

This PR also refactors how plugins are included in app or module projects. By building the plugins as AARs, the Android Gradle plugin is able to use Jetifier to translate support libraries into AndroidX libraries for all the plugin's native code. Thus, reducing the error rate when using AndroidX in apps.

This change also allows to build modules as AARs, so developers can take these artifacts and distribute them along with the native host app without the need of the Flutter tool. This is a requirement for add to app.

`flutter build aar` generates POM artifacts (XML files) which contain metadata about the native dependencies used by the plugin. This allows Gradle to resolve dependencies at the app level. The result of this new build command is a single build/outputs/repo, the local repository that contains all the generated AARs and POM files.

In a Flutter app project, this local repo is used by the Flutter Gradle plugin to resolve the plugin dependencies. In add to app case, the developer needs to configure the local repo and the dependency manually in `build.gradle`:


repositories {
    maven {
        url "<path-to-flutter-module>build/host/outputs/repo"
    }
}

dependencies {
    implementation("<package-name>:flutter_<build-mode>:1.0@aar") {
       transitive = true
    }
}

Slight cleanup of file locations in flutter_tools
to make it easier to see which files are responsible
for data reporting.

This is added as a dimension cd26

This is done via `flutter build bundle`.   As a consequence, this PR introduces a new way to disable analytics via the `FLUTTER_SUPPRESS_ANALYTICS` env flag.

Adds two new custom analytics dimensions: run_target_os_version and run_target_mode_name that are sent with each invocation of flutter run and show up in Google Analytics as "screens".

This reverts commit faec4ca3.

* Report hot reload statistic

* Lints

* Introduce custom dimensions identifiers to track hot reload stats

* Allow passing a restart reason through to analytics

* Update to avoid overlaps with other code

* Remove TODO as this is the real live value

* Improve formatting + constant name

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

This updates AppContext per the recommendations in #15352

Fixes #15352

Generate the "version" file from git tags.
Remove the old VERSION file and mentions of versions in pubspec.yaml files.
Replace the old update_versions.dart script with a new roll_dev.dart script.
Update "flutter channel".
Update "flutter upgrade", including making it transition from alpha to dev.
Update "flutter --version" and "flutter doctor".

* First version

* Prevent modification of .flutter during analytics test

* Pass in directory and override analyzer warning due to conditional import

* Review comments

* Get rid of static version methods which ignore the AppContext

* Review comments

* Review Comments

* Make branch behave the same as original implementation

* Fix tests

Previously, the usage analytics would generate a write to the user's
HOME directory during the Fuchsia build. We're tightening down the
environment in which we run the Fuchsia build, and these writes are now
more obvious.

This patch removes the usage analytics during the Fuchsia build,
avoiding the write to the user's HOME directory.

* report run target and if it is an emulator

* don't print debug

* rename parameter, remove unused variable

* fix test

* fix comment

* tweak from review, and fix analyzer error

* send custom parameters for the event, not the session

* fix mock

* use the +1 for usage

* send channel name as a custom dimension

* tweaks from review

* remove unused import

FlutterCommand.runCommand subclasses can optionally return a FlutterCommandResult which is used to append additional analytics. 

Fix flutter run timing report and add a bunch of dimensional data