fix!: Migrate from RawKeyEvent to KeyEvent (#3002)

First pass at migrating from `RawKeyEvent` and `RawKeyboard`
to `KeyEvent` and `HardwareKeyboard`.

Context:
https://docs.flutter.dev/release/breaking-changes/key-event-migration

doc/tutorials/platformer/app/lib/actors/ember.dart

@@ -44,7 +44,7 @@ class EmberPlayer extends SpriteAnimationComponent
   }
 
   @override
-  bool onKeyEvent(RawKeyEvent event, Set<LogicalKeyboardKey> keysPressed) {
+  bool onKeyEvent(KeyEvent event, Set<LogicalKeyboardKey> keysPressed) {
     horizontalDirection = 0;
     horizontalDirection += (keysPressed.contains(LogicalKeyboardKey.keyA) ||
             keysPressed.contains(LogicalKeyboardKey.arrowLeft))

doc/tutorials/platformer/app/pubspec.yaml

@@ -5,6 +5,7 @@ version: 1.0.0+1
 
 environment:
   sdk: ">=3.0.0 <4.0.0"
+  flutter: ^3.19.0
 
 dependencies:
   flame: ^1.15.0