Tweak Room Hierarchy root visibility and add loading getter

src/room-hierarchy.ts

@@ -47,7 +47,7 @@ export class RoomHierarchy {
      * @constructor
      */
     constructor(
-        private readonly root: Room,
+        public readonly root: Room,
         private readonly pageSize?: number,
         private readonly maxDepth?: number,
         private readonly suggestedOnly = false,
@@ -61,6 +61,10 @@ export class RoomHierarchy {
         return !!this.serverSupportError || !!this.nextBatch || !this._rooms;
     }
 
+    public get loading(): boolean {
+        return !!this.loadRequest;
+    }
+
     public get rooms(): IHierarchyRoom[] {
         return this._rooms;
     }