Add missing trailing commas (#28673)

* add trailing commas on list/map/parameters

* add trailing commas on Invocation with nb of arg>1

* add commas for widget containing widgets

* add trailing commas if instantiation contains trailing comma

* revert bad change
diff --git a/examples/layers/rendering/hello_world.dart b/examples/layers/rendering/hello_world.dart
index 1f49ca7..f6164d0 100644
--- a/examples/layers/rendering/hello_world.dart
+++ b/examples/layers/rendering/hello_world.dart
@@ -24,6 +24,6 @@
         // particular text direction.
         textDirection: TextDirection.ltr,
       ),
-    )
+    ),
   );
 }