129641: Fix Export button is enabled wrongly

This fixes the export button being enabled when the second step is not active in bulk access edit. The tests have been updated accordingly

src/app/shared/access-control-form-container/access-control-form-container.component.ts

@@ -156,5 +156,9 @@ export class AccessControlFormContainerComponent<T extends DSpaceObject> impleme
     this.selectableListService.deselectAll(ITEM_ACCESS_CONTROL_SELECT_BITSTREAMS_LIST_ID);
   }
 
+  isValid() {
+    return this.bitstreamAccessCmp.isValid() || this.itemAccessCmp.isValid();
+  }
+
 }