Reland "Upgrade Gradle and AGP versions to 7.5/7.2 and migrate benchmarks+examples" #108472 (#108510)

Revert "Reland "Upgrade Gradle and AGP versions to 7.5/7.2 and migrate benchmarks+examples" #108355 (#108472)" (#108488)

This reverts commit 1f8c490c.

Reland "Upgrade Gradle and AGP versions to 7.5/7.2 and migrate benchmarks+examples" #108355 (#108472)

Revert "Reland "Upgrade Gradle and AGP versions to 7.5/7.2 and migrate benchmarks+examples" (#108355)" (#108407)

This reverts commit c4b3625d.

This reverts commit ca6cecf0.

This reverts commit 9038fac9.

This reverts commit 058dfd49.

* Revert "Mark last failing test after gradle update as flaky. (#91423)"

This reverts commit 46a52d03.

* Revert "fix android template for Gradle 7 (#91411)"

This reverts commit 51d06d53.

* Revert "Add explicit version for mac and windows openjdk. (#91408)"

This reverts commit bf429f27.

* Revert "Update the openjdk version used by linux android tests. (#91405)"

This reverts commit 2144ab8b.

* Revert "Migrate to Gradle 7.0.2 / AGP 7.0.1 (#90642)"

This reverts commit b6459f9b.

This extracts the sample code out from the API doc comments, and places them in separate files on disk, allowing running of the examples locally, testing them, and building of slightly larger examples.

This reverts commit 8e73bab9.

This reverts commit 30f33d6c.

Fixes https://github.com/flutter/flutter/issues/26544

This reverts commit 751c083f.

Our buildbots need to be upgraded to a newer version of the Android SDK.

This renames the "module" template to the "application" template, and makes "application" the default. The existing "app" template is now deprecated.

flutter create also now recognizes the type of project in an existing directory, and is able to recreate it without having the template type explicitly specified (although you can still do that). It does this now by first looking in the .metadata file for the new project_type field, and if it doesn't find that, then it looks at the directory structure. Also, the .metadata file is now overwritten even on an existing directory so that 1) the project_type can be added to legacy projects, and 2) the version of Flutter that updated the project last is updated.

I also cleaned up a bunch of things in create_test.dart, added many more tests, and added an example test to the test/ directory in the generated output of the application template.

Fixes #22530
Fixes #22344

This reverts commit 59bb2dba.

This reverts commit 0f557e72.

This reverts commit dac1baf4.