Add loading spinner to room-list view

src/app/room-list/room-list.component.html

 <mat-accordion>
+  <div fxLayout="row" fxLayoutAlign="center">
+    <mat-progress-spinner *ngIf="isLoading" mode="indeterminate"></mat-progress-spinner>
+  </div>
   <mat-expansion-panel *ngFor="let room of rooms">
     <mat-expansion-panel-header>
-      <button mat-button color="primary" routerLink="/{{ baseUrl }}/room/{{ room.id }}"><mat-icon>send</mat-icon></button>
+      <button mat-button color="primary" routerLink="/{{ baseUrl }}/room/{{ room.id }}">
+        <mat-icon>send</mat-icon>
+      </button>
       <mat-panel-title>
         {{ room.shortId }}
       </mat-panel-title>

src/app/room-list/room-list.component.ts

@@ -13,6 +13,7 @@ export class RoomListComponent implements OnInit {
   rooms: Room[];
   closedRooms: Room[];
   baseUrl: string;
+  isLoading = true;
 
   constructor(
     private roomService: RoomService,
@@ -35,6 +36,7 @@ export class RoomListComponent implements OnInit {
     this.roomService.getRooms().subscribe(rooms => {
       this.rooms = rooms;
       this.closedRooms = this.rooms.filter(room => room.closed);
+      this.isLoading = false;
     });
   }
 }