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.

Fixes: #102813

Adds a checkmark style to the Cupertino Radio. Also allows the Radio.adaptive and RadioListTile.adaptive widgets to control whether they use the checkmark style for their Cupertino widgets or not.

This is how it looks in action:

https://github.com/flutter/flutter/assets/58190796/b409b270-42dd-404a-9350-d2c3e1d7fa4e

fixes https://github.com/flutter/flutter/issues/125495

The iOS will announce 'Selected, \<label\>, button' for selected radio button after this change

Create CupertinoRadio Widget