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

app/javascript/mastodon/initial_state.js

@@ -43,6 +43,7 @@
  * @property {boolean=} use_pending_items
  * @property {string} version
  * @property {string} sso_redirect
+ * @property {boolean} force_grouped_notifications
  */
 
 /**
@@ -118,6 +119,7 @@ export const criticalUpdatesPending = initialState?.critical_updates_pending;
 // @ts-expect-error
 export const statusPageUrl = getMeta('status_page_url');
 export const sso_redirect = getMeta('sso_redirect');
+export const forceGroupedNotifications = getMeta('force_grouped_notifications');
 
 /**
  * @returns {string | undefined}