This PR adds `AnimationSheetRecorder.dispose`, which disposes all the images generated by the recorder, eliminating leaks.

Fixes https://github.com/flutter/flutter/issues/133071.

Fixes https://github.com/flutter/flutter/issues/59413

This relocates `mock_canvas.dart` and `recording_canvas.dart` from `flutter/test/rendering` to `flutter_test`. 

The testing functionality afforded by mock_canvas should be available to everyone, not just the framework. :)

mock_canvas.dart needed a bit of cleanup - things like formatting and super parameters.

Reverts flutter/flutter#131368
Original PR: https://github.com/flutter/flutter/pull/131292 . The
flutter mirror was out of date and tree was closed, so the original PR
was reverted. Now should be safe to have a reland.

Reverts flutter/flutter#131292

This PR is affected by https://g-issues.skia.org/issues/40045533.

See @Piinks's [explanation](https://discord.com/channels/608014603317936148/613398423093116959/1133885989358678076):

> The mirror is probably out of sync. The failing commit introduced new changes, but they have not been updated yet. I would revert the PR until we can check the mirror. Last week it went 2+ hours out of sync so rerunning it may not green the tree for a while.

Updated golden tests in 

* ink_sparkle_test.dart
* material_test.dart
* page_test.dart
* progress_indicator_test.dart

to have M2 and M3 versions.

More info in #127064

Split from https://github.com/flutter/flutter/pull/122664 so it gets easier to review, as this is now unrelated to the `preferRound`. I'm one step from adding a width attribute, lol.

<img width="474" alt="image" src="https://user-images.githubusercontent.com/351125/226083798-71e529e9-4ae9-41de-a500-0412b989a273.png">

cc @Piinks

Add `StrokeCap` to `CircularProgressIndicator`

This reverts commit 5fd259be.

* Randomize tests, exclude tests that fail with randomization.

* Disable some more tool tests

This reverts commit b5f9612c because it is taking about 40% longer to run the tests, which is causing timeouts.

This turns on order shuffling for all tests that don't fail with it on, marking those tests that do fail with a tag so that they will be run without shuffling on.

To determine which tests fail with it on, I ran all the tests 100 times with different random shuffle seeds, and then also ran it with the date seeds from today until the end of July, and tagged all of the test suites (files) that fail, with a seed that caused them to fail.

Adds tests to the following behaviors, which have existed without tests:

- When tapping during live testing, a message is printed with widgets that contain the tap location.
- When tapping during live testing, a mark is displayed on screen on the tap location.

* add language version 2.8 in packages/flutter

* enable non-nullable analyzer flag