feat: Add onDispose to game.dart called from game_widget.dart

[munsterlander]

Description

This adds, imo, the missing piece in the event lifecycle based on all the other lifecycle work I have been doing.

Currently, when dispose is called in game_widget.dart, it calls disposeCurrentGame which has the call for onRemove, at issue though is, disposeCurrentGame is also called by didUpdateWidget if the oldWidget.game != widget.game. It may not be needed, but I feel like because FlameGame is inherently a stateless set of widgets (children of the LeafRenderObjectWidget), the hook for onRemove is muddled with what is NOT actually a dispose event. So my thought is, introduce the onDispose method to game which gets called by making disposeCurrentGame({isDispose = false}) then in the actual overridden dispose method, pass that as true, so we can then call currentGame.onDispose() after the call to currentGame.onRemove().

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.

Related Issues