Do not trigger use_build_context_synchronously on context.mounted

lib/src/rules/use_build_context_synchronously.dart

@@ -314,7 +314,9 @@ class _Visitor extends SimpleAstVisitor {
   visitPrefixedIdentifier(PrefixedIdentifier node) {
     // Getter access.
     if (isBuildContext(node.prefix.staticType, skipNullable: true)) {
-      check(node);
+      if (node.identifier.name != 'mounted') {
+        check(node);
+      }
     }
   }
 }

test_data/rules/use_build_context_synchronously.dart

@@ -295,6 +295,12 @@ class _MyState extends State<MyWidget> {
     Navigator.of(context).pushNamed('routeName'); // OK
   }
 
+  void methodWithBuildContextParameter4(BuildContext context) async {
+    await Future<void>.delayed(Duration());
+    if (!context.mounted) return;
+    await Navigator.of(context).pushNamed('routeName'); // OK
+  }
+
   void methodWithMountedFieldCheck(
       BuildContext context, WidgetStateContext stateContext) async {
     await Future<void>.delayed(Duration());