Give channel descriptions in `flutter channel`, use branch instead of upstream for channel name (#126936)

## How we determine the channel name

Historically, we used the current branch's upstream to figure out the current channel name. I have no idea why. I traced it back to https://github.com/flutter/flutter/pull/446/files where @abarth implement this and I reviewed that PR and left no comment on it at the time.

I think this is confusing. You can be on a branch and it tells you that your channel is different. That seems weird.

This PR changes the logic to uses the current branch as the channel name.

## How we display channels

The main reason this PR exists is to add channel descriptions to the `flutter channel` list:

```
ianh@burmese:~/dev/flutter/packages/flutter_tools$ flutter channel
Flutter channels:
  master (tip of tree, for contributors)
  main (tip of tree, follows master channel)
  beta (updated monthly, recommended for experienced users)
  stable (updated quarterly, for new users and for production app releases)
* foo_bar

Currently not on an official channel.
ianh@burmese:~/dev/flutter/packages/flutter_tools$
```

## Other changes

I made a few other changes while I was at it:

* If you're not on an official channel, we used to imply `--show-all`, but now we don't, we just show the official channels plus yours. This avoids flooding the screen in the case the user is on a weird channel and just wants to know what channel they're on.
* I made the tool more consistent about how it handles unofficial branches. Now it's always `[user branch]`.
* I slightly adjusted how unknown versions are rendered so it's clearer the version is unknown rather than just having the word "Unknown" floating in the output without context.
* Simplified some of the code.
* Made some of the tests more strict (checking all output rather than just some aspects of it).
* Changed the MockFlutterVersion to implement the FlutterVersion API more strictly.
* I made sure we escape the output to `.metadata` to avoid potential injection bugs (previously we just inlined the version and channel name verbatim with no escaping, which is super sketchy).
* Tweaked the help text for the `downgrade` command to be clearer.
* Removed some misleading text in some error messages.
* Made the `.metadata` generator consistent with the template file.
* Removed some obsolete code to do with the `dev` branch.

## Reviewer notes

I'm worried that there are implications to some of these changes that I am not aware of, so please don't assume I know what I'm doing when reviewing this code. :-)

Relands #126086, which was reverted by #126569.

Reverts flutter/flutter#126086.

This PR changed the interfaces of some classes, namely `AndroidSdk`, and deleted a global.

These classes had custom overrides in g3 that were not updated with a g3fix, so this PR has broken tests. See https://b.corp.google.com/issues/281945232 (non-public link)

This is the first step in unifying Java-finding logic across the tool. If curious, see #126029 for an example of what all the changes will probably entail.

Moves java-related functionality like `AndroidSdk.findJavaHome` to a new class, `Java`.

See tracking issue https://github.com/flutter/flutter/issues/126126 for more.

fixes https://github.com/flutter/flutter/issues/120405

https://github.com/flutter/flutter/issues/123917

Doc covering a broad set of issues related to android studio updating. 

https://docs.google.com/document/d/1hTXkjbUrBnXgu8NQsth1c3aEqo77rWoEj8CcsQ39wwQ/edit?pli=1#

Specifically this pr: 
- Adds new functions to find a projects AGP, Gradle and java versions,
and tests.
- Adds new functions that take versions and parse if the versions are
compatible with each other, and tests.
- Adds validator for `flutter analyze --suggestions` that evaluates the
java/gradle/agp versions and checks if they are compatible, and
integration test.
- Updates the version of gradle used by
dev/integration_tests/flutter_gallery/ to the minimum supported by java
18 so that the integration tests pass (It is unknown why the java
version is 18.9 instead of 11)
- Moves `isWithinVersionRange` to version.dart, and tests. 
- Adds FakeAndroidStudio to fakes to be used in multiple tests but does
not remove existing copies.

Metrics will be included as part of the definition of done for this bug
but not as part of this cl. It is already too big.

Known work still left in this pr: 
* Understand why analyze integration tests are failing. 


Example output if Java and gradle are not compatible: 
```
┌───────────────────────────────────────────────────────────────────┐
│ General Info                                                      │
│ [✓] App Name: espresso_example                                    │
│ [✓] Supported Platforms: android                                  │
│ [✓] Is Flutter Package: yes                                       │
│ [✓] Uses Material Design: yes                                     │
│ [✓] Is Plugin: no                                                 │
│ [✗] Java/Gradle/Android Gradle Plugin:                            │
│                                                                   │
│ Incompatible Java/Gradle versions.                                │
│                                                                   │
│ Java Version: 17.0.6, Gradle Version: 7.0.2                       │
│                                                                   │
│ See the link below for more information.                          │
│ https://docs.gradle.org/current/userguide/compatibility.html#java │
│                                                                   │
└───────────────────────────────────────────────────────────────────┘
```
Example output if Gradle and AGP are not compatible
```
┌─────────────────────────────────────────────────────────────────────────────┐
│ General Info                                                                │
│ [✓] App Name: espresso_example                                              │
│ [✓] Supported Platforms: android                                            │
│ [✓] Is Flutter Package: yes                                                 │
│ [✓] Uses Material Design: yes                                               │
│ [✓] Is Plugin: no                                                           │
│ [✗] Java/Gradle/Android Gradle Plugin: Incompatible Gradle/AGP versions.    │
│                                                                             │
│ Gradle Version: 7.0.2, AGP Version: 7.4.2                                   │
│                                                                             │
│ Update gradle to at least "7.5".                                            │
│ See the link below for more information:                                    │
│ https://developer.android.com/studio/releases/gradle-plugin#updating-gradle │
│                                                                             │
│ Incompatible Java/Gradle versions.                                          │
│                                                                             │
│ Java Version: 17.0.6, Gradle Version: 7.0.2                                 │
│                                                                             │
│ See the link below for more information:                                    │
│ https://docs.gradle.org/current/userguide/compatibility.html#java           │
│                                                                             │
└─────────────────────────────────────────────────────────────────────────────┘
```
Example output if Java/Gradle/Agp are not compatible. 
```

┌─────────────────────────────────────────────────────────────────────────────┐
│ General Info                                                                │
│ [✓] App Name: espresso_example                                              │
│ [✓] Supported Platforms: android                                            │
│ [✓] Is Flutter Package: yes                                                 │
│ [✓] Uses Material Design: yes                                               │
│ [✓] Is Plugin: no                                                           │
│ [✗] Java/Gradle/Android Gradle Plugin: Incompatible Gradle/AGP versions.    │
│                                                                             │
│ Gradle Version: 7.0.2, AGP Version: 7.4.2                                   │
│                                                                             │
│ Update gradle to at least "7.5".                                            │
│ See the link below for more information:                                    │
│ https://developer.android.com/studio/releases/gradle-plugin#updating-gradle │
│                                                                             │
│ Incompatible Java/Gradle versions.                                          │
│                                                                             │
│ Java Version: 17.0.6, Gradle Version: 7.0.2                                 │
│                                                                             │
│ See the link below for more information:                                    │
│ https://docs.gradle.org/current/userguide/compatibility.html#java           │
│                                                                             │
└─────────────────────────────────────────────────────────────────────────────┘
```

Commit messages
- Add function to gradle_utils.dart that gets the gradle version from
wrapper or system and add a test for each situation
- Add method to get agp version, add method to validate agp against
gradle version, update documentation, add tests for agp validation.
- Update dart doc for validateGradleAndAgp to describe where the info
came from and corner case behavior, create function to validate java and
gradle and hardcode return to false
- Fill out and test java gradle compatibility function in gradle_utils
- Hook up java gradle evaluateion to hasValidJavaGradleAgpVersions with
hardcoded java version
- Add java --version output parsing and tests
- Add getJavaBinary test
- Update comment in android_sdk for mac behavior with java_home -v

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] All existing and new tests are passing.

Add macos project auto migration code for FlutterApplication

flutter_tool: only enable wasm compile in master channel

* dart fix --apply

* manual fixes

* fix after merge conflicts

* review

* update flutter build command

* update tests

* fix analyze suggestions

This reverts commit 3802eb62.

Fuchsia will soon remove all support for Component Framework version 1
components (recognized by component manifests ending in `.cmx`).
Notably, some of the `flutter` tool commands for Fuchsia devices--
notably, but not limited to, those related to CFv1--are outdated, and
either do not work today or soon won't work.

This PR removes the outdated components and commands, replacing some
with the newer version, or simply removing the non-working features,
in some cases.

Co-authored-by: Christopher Fujino <christopherfujino@gmail.com>

* Switch to use xml in PlistParser

* Review feedbacks: Change dynamic to Object, remove getValueFromFile

* Add DevTools version to `flutter --version` output.

* review comments

* fix test

* add explanatory comment

* dummy commit to kick bots
Co-authored-by: Christopher Fujino <christopherfujino@gmail.com>

[flutter_tools] replace MockFlutterVersion usage with fake where possible, move from context (#77390)