feat: Implement TertiaryTapCallbacks on new event system

[luanpotter]

Description

Following up on our events master plan.

This adds TertiaryTapCallbacks and necessary infrastructure to make it work.

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

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

With TertiaryTapCallbacks following the newer patterns in flame:

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 #3900 - basically we allow for multiple callbacks to register the same detector, handling deduplication and bindings.

Also adds example, tests, and documentation.

Checklist

• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

[luanpotter]

NOTE: on my consideration around whether to rename this

while it is public, it is not really user facing - I think renaming is totally fine
problem is that it is hard to name because flutter splits primary taps as a completely different recognizer
that means we have (currently) MultiTapDispatcher (for primary)
and this for secondary + tertiary
NonPrimaryTapDispatcher is the best I came up with but isn't perfect

thoughts?