message: fix: add ng-option-marked class for custom tags
diff: </ng-template>
  </div>
  - <div class="ng-option" [class.marked]="!itemsList.markedItem" (mouseover)="itemsList.unmarkItem()" role="option" (click)="selectTag()" *ngIf="showAddTag()">
  + <div class="ng-option" [class.ng-option-marked]="!itemsList.markedItem" (mouseover)="itemsList.unmarkItem()" role="option" (click)="selectTag()" *ngIf="showAddTag()">
  <span><span class="ng-tag-label">{{addTagText}}</span>"{{filterValue}}"</span>
  </div>
  </ng-container>
  