Adds initial support for flutter create of apps and plugins. This is derived from the current FDE example app and sample plugin, adding template values where relevant.

Since the APIs/tooling/template aren't stable yet, the app template includes a version marker, which will be updated each time there's a breaking change. The build now checks that the template version matches the version known by that version of the tool, and gives a specific error message when there's a mismatch, which improves over the current breaking change experience of hitting whatever build failure the breaking change causes and having to figure out that the problem is that the runner is out of date. It also adds a warning to the create output about the fact that it won't be stable.

Plugins don't currently have a version marker since in practice this is not a significant problem for plugins yet the way it is for runners; we can add it later if that changes.

Fixes #30704

This reverts commit 8c0b43bd.

2d42c74a3 Replace Pipeline's `ProduceToFront` with `ProduceIfEmpty` to handle thread merging. (flutter/engine#17122) (#52972)

77e6d32a1 Roll src/third_party/skia f22744971516..85755f46a881 (1 commits) (flutter/engine#17225) (#52966)

* Move mouse_tracking to rendering

* Move test

6aedbb7d3 Roll src/third_party/skia 4b55ff097b9d..f22744971516 (1 commits) (flutter/engine#17224) (#52964)

8dbb8ca70 Roll src/third_party/dart 5b21a43c556c..1bab476834dc (41 commits) (flutter/engine#17219) (#52938)

fix KeySet.hashCode; enable multiple web tests

This reverts commit 11efa00f.

In certain circumstances, the .packages file or dart cache could be missing - since the tool runs from a snapshot this is otherwise fine. 

b1af234b7 Disable the use of the API_AVAILABLE macro in Skia in iOS release builds. (flutter/engine#17213) (#52924)

* Allow projects that don't have tests on every platform.
  We don't really need to enforce that random projects have
  tests on every platform.

* Add some text at the end of the shard so we know it's
  actually running all the tests.

046a4a6c2 Roll src/third_party/skia 1171d314efc7..4b55ff097b9d (2 commits) (flutter/engine#17214) (#52917)

Reland of #52091