Refactor e2e's ApiService (#7101)

* Refactor e2e's ApiService

* Fix bits here and there

* [ci:force] Remove unused imports

* [ci:force] Extract shared part from adf-testing

* [ci:force] Extract StringUtils as well

* Make protractor's Logger not have duplicated code

* [ci:force]

e2e/process-services/form/attach-file-widget-start-task-app.e2e.ts

@@ -15,8 +15,7 @@
  * limitations under the License.
  */
 
-import {
-    ApiService,
+import { createApiService,
     ApplicationsUtil,
     LoginPage,
     UserModel,
@@ -39,7 +38,7 @@ describe('Start Task - Task App', () => {
     const taskPage = new TasksPage();
     const navigationBarPage = new NavigationBarPage();
 
-    const apiService = new ApiService();
+    const apiService = createApiService();
     const usersActions = new UsersActions(apiService);
     const applicationService = new ApplicationsUtil(apiService);