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/widgets/spinning_mixed.dart b/examples/layers/widgets/spinning_mixed.dart
index 4801ac7..b9f4d1c 100644
--- a/examples/layers/widgets/spinning_mixed.dart
+++ b/examples/layers/widgets/spinning_mixed.dart
@@ -26,7 +26,7 @@
     return Expanded(
       child: Container(
         color: color,
-      )
+      ),
     );
   }
 }