test: refactor many test suites to use testUtils/initializeMocks (#2067)

Simplifies a bunch of test code by converting it to use our handy testUtils module.

None of the app code is change, just test code. And none of the test cases are modified in any meaningful way - this just simplifies the setup/cleanup significantly.

src/course-unit/add-component/AddComponent.test.jsx

@@ -1,16 +1,14 @@
 /* eslint-disable react/prop-types */
-import MockAdapter from 'axios-mock-adapter';
-import {
-  act, render, screen, waitFor, within,
-} from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 
-import { initializeMockApp } from '@edx/frontend-platform';
-import { AppProvider } from '@edx/frontend-platform/react';
-import { IntlProvider } from '@edx/frontend-platform/i18n';
-import { getAuthenticatedHttpClient } from '@edx/frontend-platform/auth';
-
-import initializeStore from '../../store';
+import {
+  act,
+  render,
+  screen,
+  waitFor,
+  within,
+  initializeMocks,
+} from '../../testUtils';
 import { executeThunk } from '../../utils';
 import { fetchCourseSectionVerticalData } from '../data/thunk';
 import { getCourseSectionVerticalApiUrl } from '../data/api';
@@ -59,35 +57,23 @@ jest.mock('../../generic/hooks/context/hooks', () => ({
 }));
 
 const renderComponent = (props) => render(
-  <AppProvider store={store}>
-    <IntlProvider locale="en">
-      <IframeProvider>
-        <AddComponent
-          blockId={blockId}
-          isUnitVerticalType
-          parentLocator={blockId}
-          addComponentTemplateData={{}}
-          handleCreateNewCourseXBlock={handleCreateNewCourseXBlockMock}
-          {...props}
-        />
-      </IframeProvider>
-    </IntlProvider>
-  </AppProvider>,
+  <IframeProvider>
+    <AddComponent
+      blockId={blockId}
+      isUnitVerticalType
+      parentLocator={blockId}
+      addComponentTemplateData={{}}
+      handleCreateNewCourseXBlock={handleCreateNewCourseXBlockMock}
+      {...props}
+    />
+  </IframeProvider>,
 );
 
 describe('<AddComponent />', () => {
   beforeEach(async () => {
-    initializeMockApp({
-      authenticatedUser: {
-        userId: 3,
-        username: 'abc123',
-        administrator: true,
-        roles: [],
-      },
-    });
-
-    store = initializeStore();
-    axiosMock = new MockAdapter(getAuthenticatedHttpClient());
+    const mocks = initializeMocks();
+    axiosMock = mocks.axiosMock;
+    store = mocks.reduxStore;
     axiosMock
       .onGet(getCourseSectionVerticalApiUrl(blockId))
       .reply(200, courseSectionVerticalMock);