add seatIsSelected to SelectedSeatService, so seats cannot be interacted with while cooking/reservation

src/app/selected-seats.service.ts

@@ -6,6 +6,7 @@ import {Sitzplatz} from '@infinimotion/model-frontend';
 })
 export class SelectedSeatsService {
   private selectedSeatsList: Sitzplatz[] = [];
+  private seatIsSelectable: boolean = true;
 
   pushSelectedSeat(selectedSeat: Sitzplatz): void {
     this.selectedSeatsList.push(selectedSeat);
@@ -35,4 +36,16 @@ export class SelectedSeatsService {
     //}
   }
 
+  getSeatIsSelected(): boolean{
+    return this.seatIsSelectable;
+  }
+
+  setSeatIsSelectableTrue(): void {
+    this.seatIsSelectable = true;
+  }
+
+  setSeatIsSelectableFalse(): void {
+    this.seatIsSelectable = false;
+  }
+
 }