Refactor bonus token dialog header for lecturers

src/app/components/creator/_dialogs/bonus-token/bonus-token.component.html

 <div mat-dialog-content xmlns="http://www.w3.org/1999/html">
   <h2 class="oldtypo-h2">{{'room-page.bonus-token-header' | translate }}</h2>
-  <h3 class="oldtypo-h3">{{room.name}} - {{room.shortId.slice(0, 4)}} {{room.shortId.slice(4, 8)}}</h3>
+  <h3 class="oldtypo-h3">&raquo;{{room.name}}&laquo;</h3>
+  <h3>{{ 'room-page.session-id' | translate}}: {{room.shortId.slice(0, 4)}} {{room.shortId.slice(4, 8)}}</h3>
   <mat-divider></mat-divider>
   <div *ngIf="bonusTokens.length >= 1">
     <div fxLayout="row" *ngFor="let bonusToken of bonusTokens; index as i" class="token">