Notification Consistency

Make sure that the new rules for counting notifications for muted, mention and low priority rooms is applied consistently to the room list, space drawer and the task manager notification badge

implements #644

src/spacehierarchycache.h

@@ -69,6 +69,11 @@ public:
      */
     qsizetype notificationCountForSpace(const QString &spaceId);
 
+    /**
+     * @brief Whether any of the child rooms have highlight notifications.
+     */
+    bool spaceHasHighlightNotifications(const QString &spaceId);
+
     /**
      * @brief Returns whether the room is a child space of any space.
      *