Migrate comment form specs to Jest & VTU

Also:

- Moved issue_show/helpers and notes/mock_data to frontend specs
directory

spec/frontend/issue_show/helpers.js

+// eslint-disable-next-line import/prefer-default-export
+export const keyboardDownEvent = (code, metaKey = false, ctrlKey = false) => {
+  const e = new CustomEvent('keydown');
+
+  e.keyCode = code;
+  e.metaKey = metaKey;
+  e.ctrlKey = ctrlKey;
+
+  return e;
+};

spec/frontend/notes/components/discussion_actions_spec.js

 import createStore from '~/notes/stores';
 import { shallowMount, mount, createLocalVue } from '@vue/test-utils';
-import { discussionMock } from '../../../javascripts/notes/mock_data';
+import { discussionMock } from '../../notes/mock_data';
 import DiscussionActions from '~/notes/components/discussion_actions.vue';
 import ReplyPlaceholder from '~/notes/components/discussion_reply_placeholder.vue';
 import ResolveDiscussionButton from '~/notes/components/discussion_resolve_button.vue';

spec/frontend/notes/components/discussion_notes_spec.js

@@ -8,11 +8,7 @@ import PlaceholderSystemNote from '~/vue_shared/components/notes/placeholder_sys
 import SystemNote from '~/vue_shared/components/notes/system_note.vue';
 import TimelineEntryItem from '~/vue_shared/components/notes/timeline_entry_item.vue';
 import createStore from '~/notes/stores';
-import {
-  noteableDataMock,
-  discussionMock,
-  notesDataMock,
-} from '../../../javascripts/notes/mock_data';
+import { noteableDataMock, discussionMock, notesDataMock } from '../../notes/mock_data';
 
 const localVue = createLocalVue();
 

spec/frontend/notes/components/note_app_spec.js

@@ -9,7 +9,7 @@ import createStore from '~/notes/stores';
 import '~/behaviors/markdown/render_gfm';
 import { setTestTimeout } from 'helpers/timeout';
 // TODO: use generated fixture (https://gitlab.com/gitlab-org/gitlab-foss/issues/62491)
-import * as mockData from '../../../javascripts/notes/mock_data';
+import * as mockData from '../../notes/mock_data';
 
 setTestTimeout(1000);
 

spec/frontend/vue_shared/components/notes/placeholder_note_spec.js

 import Vue from 'vue';
 import issuePlaceholderNote from '~/vue_shared/components/notes/placeholder_note.vue';
 import createStore from '~/notes/stores';
-import { userDataMock } from '../../../../javascripts/notes/mock_data';
+import { userDataMock } from '../../../notes/mock_data';
 
 describe('issue placeholder system note component', () => {
   let store;

spec/javascripts/issue_show/helpers.js

-// eslint-disable-next-line import/prefer-default-export
-export const keyboardDownEvent = (code, metaKey = false, ctrlKey = false) => {
-  const e = new CustomEvent('keydown');
-
-  e.keyCode = code;
-  e.metaKey = metaKey;
-  e.ctrlKey = ctrlKey;
-
-  return e;
-};
+export * from '../../frontend/issue_show/helpers.js';