feat: registered BallScorePointsCallback in PinballGame

lib/game/pinball_game.dart

@@ -1,4 +1,10 @@
 import 'package:flame_bloc/flame_bloc.dart';
 import 'package:flame_forge2d/forge2d_game.dart';
+import 'package:pinball/game/game.dart';
 
-class PinballGame extends Forge2DGame with FlameBloc {}
+class PinballGame extends Forge2DGame with FlameBloc {
+  @override
+  Future<void> onLoad() async {
+    addContactCallback(BallScorePointsCallback());
+  }
+}

test/game/pinball_game_test.dart

@@ -0,0 +1,10 @@
+import 'package:flame_test/flame_test.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('PinballGame', () {
+    // TODO(alestiago): test if [PinballGame] registers [BallScorePointsCallback]
+    // once the following issue is resolved:
+    // https://github.com/flame-engine/flame/issues/1416
+  });
+}