Added ExpansionTileController - #123298

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final ExpansionTileController controller = ExpansionTileController();

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        ExpansionTile(
          controller: controller,
          title: const Text('Collapsible menu'),
          children: const <Widget>[
            Text('Menu'),
          ],
        ),
        ElevatedButton(
          onPressed: () {
            if (controller.isExpanded) {
              controller.collapse();
            } else {
              controller.expand();
            }
          },
          child: const Text('TOGGLE MENU'),
        )
      ],
    );
  }
}