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

dev/manual_tests/lib/material_arc.dart

diff --git a/dev/manual_tests/lib/material_arc.dart b/dev/manual_tests/lib/material_arc.dart
index 23fae24..5e16d64 100644
--- a/dev/manual_tests/lib/material_arc.dart
+++ b/dev/manual_tests/lib/material_arc.dart
@@ -48,7 +48,7 @@
 class _PointDemoPainter extends CustomPainter {
   _PointDemoPainter({
     Animation<double> repaint,
-    this.arc
+    this.arc,
   }) : _repaint = repaint, super(repaint: repaint);
 
   final MaterialPointArcTween arc;
@@ -202,7 +202,7 @@
           key: _painterKey,
           foregroundPainter: _PointDemoPainter(
             repaint: _animation,
-            arc: arc
+            arc: arc,
           ),
           // Watch out: if this IgnorePointer is left out, then gestures that
           // fail _PointDemoPainter.hitTest() will still be recognized because
@@ -213,12 +213,12 @@
               child: Text(
                 'Tap the refresh button to run the animation. Drag the green '
                 "and red points to change the animation's path.",
-                style: Theme.of(context).textTheme.caption.copyWith(fontSize: 16.0)
-              )
-            )
-          )
-        )
-      )
+                style: Theme.of(context).textTheme.caption.copyWith(fontSize: 16.0),
+              ),
+            ),
+          ),
+        ),
+      ),
     );
   }
 }
@@ -226,7 +226,7 @@
 class _RectangleDemoPainter extends CustomPainter {
   _RectangleDemoPainter({
     Animation<double> repaint,
-    this.arc
+    this.arc,
   }) : _repaint = repaint, super(repaint: repaint);
 
   final MaterialRectArcTween arc;
@@ -350,11 +350,11 @@
       _screenSize = screenSize;
       _begin = Rect.fromLTWH(
         screenSize.width * 0.5, screenSize.height * 0.2,
-        screenSize.width * 0.4, screenSize.height * 0.2
+        screenSize.width * 0.4, screenSize.height * 0.2,
       );
       _end = Rect.fromLTWH(
         screenSize.width * 0.1, screenSize.height * 0.4,
-        screenSize.width * 0.3, screenSize.height * 0.3
+        screenSize.width * 0.3, screenSize.height * 0.3,
       );
     }
 
@@ -375,7 +375,7 @@
           key: _painterKey,
           foregroundPainter: _RectangleDemoPainter(
             repaint: _animation,
-            arc: arc
+            arc: arc,
           ),
           // Watch out: if this IgnorePointer is left out, then gestures that
           // fail _RectDemoPainter.hitTest() will still be recognized because
@@ -386,12 +386,12 @@
               child: Text(
                 'Tap the refresh button to run the animation. Drag the rectangles '
                 "to change the animation's path.",
-                style: Theme.of(context).textTheme.caption.copyWith(fontSize: 16.0)
-              )
-            )
-          )
-        )
-      )
+                style: Theme.of(context).textTheme.caption.copyWith(fontSize: 16.0),
+              ),
+            ),
+          ),
+        ),
+      ),
     );
   }
 }
@@ -426,13 +426,13 @@
       _ArcDemo('POINT', (_ArcDemo demo) {
         return _PointDemo(
           key: demo.key,
-          controller: demo.controller
+          controller: demo.controller,
         );
       }, this),
       _ArcDemo('RECTANGLE', (_ArcDemo demo) {
         return _RectangleDemo(
           key: demo.key,
-          controller: demo.controller
+          controller: demo.controller,
         );
       }, this),
     ];
@@ -466,9 +466,9 @@
           },
         ),
         body: TabBarView(
-          children: _allDemos.map<Widget>((_ArcDemo demo) => demo.builder(demo)).toList()
-        )
-      )
+          children: _allDemos.map<Widget>((_ArcDemo demo) => demo.builder(demo)).toList(),
+        ),
+      ),
     );
   }
 }