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.

This is a follow up to the following pull requests:
- https://github.com/flutter/flutter/pull/124514

I was finally able to reproduce this bug and found out why it was happening. Consider this code:

```dart
GestureDetector(
  behavior: HitTestBehavior.translucent,
  // Note: Make sure onTap is not null to ensure events
  // are captured by `GestureDetector`
  onTap: () {},
  child: _shouldShowSlider
    ? Slider(value: _value, onChanged: _handleSlide)
    : const SizedBox.shrink().
)
```

Runtime exception happens when:

1. User taps and holds the Slider (drag callback captured by `GestureDetector`)
2. `_shouldShowSlider` changes to false, Slider disappears and unmounts, and unregisters `_handleSlide`. But the callback is still registered by `GestureDetector`
3. Users moves finger as if Slider were still there
4. Drag callback is invoked, `_SliderState.showValueIndicator` is called
5. Exception - Slider is already disposed

This pull request fixes it by adding a mounted check inside `_SliderState.showValueIndicator` to ensure the Slider is actually mounted at the time of invoking drag event callback. I've added a unit test that will fail without this change.

The error stack trace is:

```
The following assertion was thrown while handling a gesture:
This widget has been unmounted, so the State no longer has a context (and should be considered
defunct).
Consider canceling any active work during "dispose" or using the "mounted" getter to determine if
the State is still active.

When the exception was thrown, this was the stack:
#0      State.context.<anonymous closure> (package:flutter/src/widgets/framework.dart:950:9)
#1      State.context (package:flutter/src/widgets/framework.dart:956:6)
#2      _SliderState.showValueIndicator (package:flutter/src/material/slider.dart:968:18)
#3      _RenderSlider._startInteraction (package:flutter/src/material/slider.dart:1487:12)
#4      _RenderSlider._handleDragStart (package:flutter/src/material/slider.dart:1541:5)
#5      DragGestureRecognizer._checkStart.<anonymous closure> (package:flutter/src/gestures/monodrag.dart:531:53)
#6      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:275:24)
#7      DragGestureRecognizer._checkStart (package:flutter/src/gestures/monodrag.dart:531:7)
#8      DragGestureRecognizer._checkDrag (package:flutter/src/gestures/monodrag.dart:498:5)
#9      DragGestureRecognizer.acceptGesture (package:flutter/src/gestures/monodrag.dart:431:7)
#10     _CombiningGestureArenaMember.acceptGesture (package:flutter/src/gestures/team.dart:45:14)
#11     GestureArenaManager._resolveInFavorOf (package:flutter/src/gestures/arena.dart:281:12)
#12     GestureArenaManager._resolve (package:flutter/src/gestures/arena.dart:239:9)
#13     GestureArenaEntry.resolve (package:flutter/src/gestures/arena.dart:53:12)
#14     _CombiningGestureArenaMember._resolve (package:flutter/src/gestures/team.dart:85:15)
#15     _CombiningGestureArenaEntry.resolve (package:flutter/src/gestures/team.dart:19:15)
#16     OneSequenceGestureRecognizer.resolve (package:flutter/src/gestures/recognizer.dart:375:13)
#17     DragGestureRecognizer.handleEvent (package:flutter/src/gestures/monodrag.dart:414:13)
#18     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:98:12)
#19     PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:143:9)
#20     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:625:13)
#21     PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:141:18)
#22     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:127:7)
#23     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:488:19)
#24     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:468:22)
#25     RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:439:11)
#26     GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:413:7)
#27     GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:376:5)
#28     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:323:7)
#29     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:292:9)
#30     _invoke1 (dart:ui/hooks.dart:186:13)
#31     PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:433:7)
#32     _dispatchPointerDataPacket (dart:ui/hooks.dart:119:31)

Handler: "onStart"
Recognizer:
  HorizontalDragGestureRecognizer#a5df2
```

*List which issues are fixed by this PR. You must list at least one issue.*

Internal bug: b/273666179, b/192329942

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

fixes https://github.com/flutter/flutter/issues/129016

Fixed slider value indicator not disappearing after a bit on desktop platform when slider is clicked not dragged (#128137)

In slider.dart within the _startInteraction method and within the below conditional.

"if (!_active && !hasFocus &&
_state.valueIndicatorController.status == AnimationStatus.completed)"

**Changed to:**

"f (!_active &&
_state.valueIndicatorController.status == AnimationStatus.completed)"
This allows the value indicator to disappear after a bit when clicked instead of dragged on Desktop platform. 

I also added a test in slider_test.dart to detect the bug if it ever returns.

Fixes https://github.com/flutter/flutter/issues/123313

Updates most of the unit tests in the packages/flutter/test/material folder so that they'll pass if ThemeData.useMaterial3 defaults to true.

All of the tests have wired useMaterial3 to false and will need to be updated with a M3 version.

related to #127064

fixes https://github.com/flutter/flutter/issues/127795

fixes https://github.com/flutter/flutter/issues/123315
--------

This PR makes changes to the _actionHandler function used on the Slider.Dart Widget for Key Events. It ensures onChangeStart is called at the beginning of a Key Event and onChangeEnd at the end of one. This PR includes a test for the changes made.
I ran all existing tests after my changes were made and they passed.

Fixes #122250. This PR is to make sure all the MaterialStateProperty defaults are able to correctly resolve different states. 
* When a widget is pressed, it is also hovered, so we need to put the `MaterialState.pressed` check before `MaterialState.hovered`. 
* When a widget is focused, the widget should still be able to be hovered, so we should check `MaterialState.hovered` before `MaterialState.focused`.
* There are also cases like in _InputDecoratorDefaultsM3, the `MaterialState.disabled` should be checked before `MaterialState.error`.

 the order should be disabled, (error), pressed, hovered, focused.

design doc: https://docs.flutter.dev/go/permissible-slider-interaction

closes #113370

open questions:
  - No, as `SliderInteraction.none` doesn't exist anymore.
  - Yes (done)
  - Yes.
    - SliderInteraction
    - SliderAction
    - Slider.allowedInteraction
    - Slider.permissibleInteraction
    - Slider.interaction
    - Slider.allowedAction
    - Slider.permittedAction

* Fix typos

* lowercase animated & opacity

* Undo typo fix

---------
Co-authored-by: Michael Goderbauer <goderbauer@google.com>

* fix a Slider theme update bug

* Code review feedback

* Check whether slider is unmounted before interaction

* Update slider.dart

* Update Slider

* Add test

* Update slider_test.dart

* Update packages/flutter/test/material/slider_test.dart
Co-authored-by: Taha Tesser <tessertaha@gmail.com>
Co-authored-by: Taha Tesser <tessertaha@gmail.com>

This reverts commit 8473da22.

Fixes #103965

* Use `curly_braces_in_flow_control_structures` for `material`

* include test/material

* add back removed comments

Updating the Slider Widget to allow up and down arrow keys to navigate out of the slider when in directional NavigationMode. (#103149)

Microsoft Active Accessibility (MSAA) does not include
increment/decrement keyboard shortcuts for manipulating sliders and
other similar controls. To make up for this, we give the slider keyboard
focus when it gains accessibility focus so that the user can use the
arrow keys to manipulate the slider.

Issue: https://github.com/flutter/flutter/issues/77838

This reverts commit 5fd259be.

This reverts commit d056500b.

This reverts commit 31de052e.