Add android-reviewers to CODEOWNERS (#170157)

Mirror GitHub team-android labeller to android-reviewer CODEOWNERS so
that group is automatically put on Android PRs.

Add tools android and gradle files. Also add the Android embedder.

You can run `git ls-files packages/flutter_tools/**/*android*` etc to
see which files are included.

## 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].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

.github/labeler.yml

@@ -205,10 +205,15 @@ platform-windows:
   - changed-files:
     - any-glob-to-any-file:
       - docs/contributing/**/*
+
+# Keep this synced with CODEOWNERS.
 team-android:
   - changed-files:
     - any-glob-to-any-file:
       - docs/platform/android/**/*
+      - engine/src/flutter/shell/platform/android/**/*
+      - packages/flutter_tools/**/*android*
+      - packages/flutter_tools/**/*gradle*
 
 team-ecosystem:
   - changed-files:

CODEOWNERS

@@ -32,6 +32,12 @@
 /engine/src/flutter/shell/platform/embedder/embedder.h @cbracken @chinmaygarde @loic-sharma
 /engine/src/flutter/shell/platform/embedder/tests/embedder_frozen.h @cbracken @chinmaygarde @loic-sharma
 
+# Android team - keep this synced with .github/labeler.yml's team-android section.
+/docs/platform/android/** @flutter/android-reviewers
+/engine/src/flutter/shell/platform/android/** @flutter/android-reviewers
+/packages/flutter_tools/**/*android* @flutter/android-reviewers
+/packages/flutter_tools/**/*gradle* @flutter/android-reviewers
+
 # iOS team - keep this synced with .github/labeler.yml's team-ios section.
 /engine/src/flutter/shell/platform/darwin/common/ @flutter/ios-reviewers
 /engine/src/flutter/shell/platform/darwin/ios/framework/ @flutter/ios-reviewers