Split analysis steps out of dev/bots/test.dart into dev/bots/analyze.…

…dart (flutter#21174)

* Split analysis steps out of dev/bots/test.dart into dev/bots/analyze.dart.

This allows to run analysis step with command line arguments that are only applicable to flutter analyze(like --dart-sdk, needed for dart-flutter-engine head-head-head bot).

* Add forgotten dev/bots/analyze.dart

* Refactor common code from analyze.dart and test.dart into run_command.dart

* Remove comments, add header

.cirrus.yml

@@ -43,10 +43,8 @@ task:
         ANDROID_GALLERY_UPLOAD_KEY: ENCRYPTED[0b3e681b4507aec433ef29c79b715f15f8c75ecd25315ea286b0b2bcb8b28d578634eead5aa2c54086a25e8da1bb219a]
       test_script: ./dev/bots/deploy_gallery.sh
     - name: analyze
-      env:
-        SHARD: analyze
       test_script:
-        - dart ./dev/bots/test.dart
+        - dart ./dev/bots/analyze.dart
     - name: tests-linux
       env:
         SHARD: tests

CONTRIBUTING.md

@@ -129,7 +129,7 @@ which provides flutter-specific extensions on top of [package:test](https://pub.
 option to start the test in a paused state and wait for connection from a debugger. This option lets you
 set breakpoints before the test runs.
 
-To run all the tests for the entire Flutter repository, the same way that Cirrus runs them, run `dart dev/bots/test.dart`.
+To run analysis and all the tests for the entire Flutter repository, the same way that Cirrus runs them, run `dart dev/bots/test.dart` and `dart dev/bots/analyze.dart`.
 
 If you've built [your own flutter engine](#working-on-the-engine-and-the-framework-at-the-same-time), you
 can pass `--local-engine` to change what flutter shell `flutter test` uses. For example,