Add loading spinner to creator-room view

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

 <div fxLayout="column" fxLayoutAlign="start" fxLayoutGap="20px" fxFill>
   <div fxLayout="row" fxLayoutAlign="center">
+    <mat-progress-spinner *ngIf="isLoading" mode="indeterminate"></mat-progress-spinner>
     <mat-card *ngIf="room && !modify" class="input-form">
       <mat-card-header>
         <mat-card-title>