Add ability for admins to force grouped notifications in web UI (#31610)

app/javascript/mastodon/features/notifications_wrapper.jsx

@@ -1,9 +1,10 @@
 import Notifications from 'mastodon/features/notifications';
 import Notifications_v2 from 'mastodon/features/notifications_v2';
+import { selectUseGroupedNotifications } from 'mastodon/selectors/settings';
 import { useAppSelector } from 'mastodon/store';
 
 export const NotificationsWrapper = (props) => {
-  const optedInGroupedNotifications = useAppSelector((state) => state.getIn(['settings', 'notifications', 'groupingBeta'], false));
+  const optedInGroupedNotifications = useAppSelector(selectUseGroupedNotifications);
 
   return (
     optedInGroupedNotifications ? <Notifications_v2 {...props} /> : <Notifications {...props} />