Adds checking for trailling commas on the project (#670)

* Testing a new linter option for trailling commas

* Checking trailling commas on linter

doc/examples/spritesheet/lib/main.dart

@@ -28,7 +28,9 @@ class MyGame extends BaseGame {
     final spriteSize = Vector2(80.0, 90.0);
 
     final vampireComponent = SpriteAnimationComponent.fromSpriteAnimation(
-        spriteSize, vampireAnimation)
+      spriteSize,
+      vampireAnimation,
+    )
       ..x = 150
       ..y = 100;