93889: Invalidate EPerson when their Groups change and groups when a subgroup is added

src/app/shared/testing/data-service.stub.ts

@@ -0,0 +1,9 @@
+import { Observable, of as observableOf } from 'rxjs';
+
+export class DataServiceStub {
+
+  invalidateByHref(_href: string): Observable<boolean> {
+    return observableOf(true);
+  }
+
+}