Pass key into _BottomNavigationTile

Adding a optional key parameter to BottomNavigationBarItem to be passed through to _BottomNavigationTile.
This will allow easier testing in some scenarios, and fix the splash appearing on the wrong tile.

https://github.com/flutter/flutter/issues/139615
https://github.com/flutter/flutter/issues/34833

This PR wraps the `label` with `IntrinsicWidth` and then `Flexible` which allows DefaulTextStyle `TextOverflow.ellipsis` to work. Wrapping `label` directly with `Flexible` brings more space between `icon` and `label`. `IntrinsicWidth` fixes this by giving reasonable width.

Fixes #112163

This PR removes the call to `InkSparkle.constantTurbulenceSeedSplashFactory` which was introduced in https://github.com/flutter/flutter/pull/137998.

This is now obsolete since https://github.com/flutter/flutter/pull/138757 was merged and InkSparkle randomness is no more active in tests.

This is a reland of https://github.com/flutter/flutter/pull/136624 which was reverted because one new M3 golden test failed. The failure was related to the ink sparkle animation.

Ink sparkle is the M3 default animation, it does not play well with golden because it introduces an element of randomness.
One way to avoid this randomness is to use the `InkSparkle.constantTurbulenceSeedSplashFactory`.

This PR has two commits:
- the first one is the original PR (https://github.com/flutter/flutter/pull/136624).
- the second one updates the failing test using `InkSparkle.constantTurbulenceSeedSplashFactory`.

Reverts flutter/flutter#136624
Initiated by: HansMuller
This change reverts the following previous change:
Original Description:
This PR updates `BottomNavigationBar` unit tests for M3 migration.

More info in https://github.com/flutter/flutter/issues/127064

It was somewhat complex because existing tests relied on a lot of magic numbers.

This PR updates `BottomNavigationBar` unit tests for M3 migration.

More info in https://github.com/flutter/flutter/issues/127064

It was somewhat complex because existing tests relied on a lot of magic numbers.

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.

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

* Use `curly_braces_in_flow_control_structures` for `material`

* include test/material

* add back removed comments

This reverts commit 5fd259be.

This reverts commit d056500b.

This reverts commit 31de052e.

This reverts commit e2490f29.