Move last remaining module out of src/sidebar/directive/test

Move Angular component testing utilities into
src/sidebar/components/test and rename the module to make it clear that
it contains Angular-specific code which we can delete once all
components are converted.

src/sidebar/components/test/annotation-test.js

 import angular from 'angular';
 
-import * as util from '../../directive/test/util';
+import * as util from './angular-util';
 import events from '../../events';
 import * as fixtures from '../../test/annotation-fixtures';
 import annotationComponent from '../annotation';

src/sidebar/components/test/annotation-thread-test.js

 import angular from 'angular';
 
-import * as util from '../../directive/test/util';
+import * as util from './angular-util';
 import * as fixtures from '../../test/annotation-fixtures';
 import annotationThread from '../annotation-thread';
 import moderationBanner from '../moderation-banner';

src/sidebar/components/test/thread-list-test.js

@@ -2,7 +2,7 @@ import angular from 'angular';
 import immutable from 'seamless-immutable';
 import EventEmitter from 'tiny-emitter';
 
-import * as util from '../../directive/test/util';
+import * as util from './angular-util';
 import events from '../../events';
 import threadList, { $imports } from '../thread-list';
 

src/sidebar/util/test/wrap-react-component-test.js

@@ -4,7 +4,7 @@ import { useContext } from 'preact/hooks';
 import propTypes from 'prop-types';
 
 import { Injector } from '../../../shared/injector';
-import { createDirective } from '../../directive/test/util';
+import { createDirective } from '../../components/test/angular-util';
 import { ServiceContext } from '../service-context';
 import wrapReactComponent from '../wrap-react-component';