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/packages/flutter_tools/test/emulator_test.dart b/packages/flutter_tools/test/emulator_test.dart
index 71469fb..2fdef5b 100644
--- a/packages/flutter_tools/test/emulator_test.dart
+++ b/packages/flutter_tools/test/emulator_test.dart
@@ -53,7 +53,7 @@
       final List<Emulator> emulators = <Emulator>[
         emulator1,
         emulator2,
-        emulator3
+        emulator3,
       ];
       final TestEmulatorManager testEmulatorManager =
           TestEmulatorManager(emulators);
@@ -204,7 +204,7 @@
     bool includeParentEnvironment = true,
     bool runInShell = false,
     Encoding stdoutEncoding = systemEncoding,
-    Encoding stderrEncoding = systemEncoding
+    Encoding stderrEncoding = systemEncoding,
   }) {
     final String program = command[0];
     final List<String> args = command.sublist(1);