Added scaffoldMessangerKey proprty to GetMaterialApp

@@ -13,6 +13,7 @@ class GetMaterialApp extends StatelessWidget {
   const GetMaterialApp({
     Key? key,
     this.navigatorKey,
+    this.scaffoldMessengerKey,
     this.home,
     Map<String, Widget Function(BuildContext)> this.routes =
         const <String, WidgetBuilder>{},
@@ -71,6 +72,7 @@ class GetMaterialApp extends StatelessWidget {
         super(key: key);
 
   final GlobalKey<NavigatorState>? navigatorKey;
+  final GlobalKey<ScaffoldMessengerState>? scaffoldMessengerKey;
   final Widget? home;
   final Map<String, WidgetBuilder>? routes;
   final String? initialRoute;
@@ -128,6 +130,7 @@ class GetMaterialApp extends StatelessWidget {
   GetMaterialApp.router({
     Key? key,
     this.routeInformationProvider,
+    this.scaffoldMessengerKey,
     RouteInformationParser<Object>? routeInformationParser,
     RouterDelegate<Object>? routerDelegate,
     this.backButtonDispatcher,
@@ -252,6 +255,7 @@ class GetMaterialApp extends StatelessWidget {
           ? MaterialApp.router(
               routerDelegate: routerDelegate!,
               routeInformationParser: routeInformationParser!,
+              scaffoldMessengerKey: scaffoldMessengerKey,
               backButtonDispatcher: backButtonDispatcher,
               routeInformationProvider: routeInformationProvider,
               key: _.unikey,