feat: Implement TertiaryTapCallbacks on new event system (#3899)

Following up on [our events master
plan](https://docs.google.com/document/d/1nBUup9QCPioVwWL1zs79z1hWF882tAYfNywFMdye2Qc).

This adds `TertiaryTapCallbacks` and necessary infrastructure to make it
work.

This replaces the old `TertiaryTapDetector` (which we can deprecate
later), e.g.:

```dart
class MyGame extends FlameGame with TertiaryTapDetector {
  @override
  void onTertiaryTapDown(TapDownInfo info) {
    // game-level handling
  }
}
```

With `TertiaryTapCallbacks` following the newer patterns in flame:

```dart
class MiddleClickSquare extends RectangleComponent with TertiaryTapCallbacks {
  @override
  void onTertiaryTapDown(TertiaryTapDownEvent event) {
    // component-level handling, with hit detection
  }

  @override
  void onTertiaryTapUp(TertiaryTapUpEvent event) {
    // tertiary tap finished
  }
}
```

Note that this new detector uses the same dispatcher as secondary, as
they share the same underlying flutter recognizer. This is in line with
my refactor on https://github.com/flame-engine/flame/pull/3900 -
basically we allow for multiple callbacks to register the same detector,
handling deduplication and bindings.

Also adds example, tests, and documentation.