Move jquery.atwho initialization away from main.js

app/assets/javascripts/commons/jquery.js

@@ -2,6 +2,4 @@ import 'jquery';
 
 // common jQuery plugins
 import 'jquery-ujs';
-import 'jquery.caret'; // must be imported before at.js
-import '@gitlab/at.js';
 import 'vendor/jquery.scrollTo';

app/assets/javascripts/gfm_auto_complete.js

 import $ from 'jquery';
-import '@gitlab/at.js';
+import '~/lib/utils/jquery_at_who';
 import { escape, template } from 'lodash';
 import SidebarMediator from '~/sidebar/sidebar_mediator';
 import glRegexp from './lib/utils/regexp';

app/assets/javascripts/lib/utils/jquery_at_who.js

+import 'jquery';
+import 'jquery.caret'; // required by at.js
+import '@gitlab/at.js';

app/assets/javascripts/notes.js

@@ -11,11 +11,10 @@ old_notes_spec.js is the spec for the legacy, jQuery notes application. It has n
  */
 
 import $ from 'jquery';
+import '~/lib/utils/jquery_at_who';
 import { escape, uniqueId } from 'lodash';
 import Cookies from 'js-cookie';
 import Autosize from 'autosize';
-import 'jquery.caret'; // required by at.js
-import '@gitlab/at.js';
 import Vue from 'vue';
 import { GlDeprecatedSkeletonLoading as GlSkeletonLoading } from '@gitlab/ui';
 import AjaxCache from '~/lib/utils/ajax_cache';

ee/app/assets/javascripts/gfm_auto_complete.js

 import $ from 'jquery';
+import '~/lib/utils/jquery_at_who';
 import GfmAutoComplete from '~/gfm_auto_complete';
 
 /**

spec/frontend/gfm_auto_complete_spec.js

 /* eslint no-param-reassign: "off" */
 
 import $ from 'jquery';
+import '~/lib/utils/jquery_at_who';
 import GfmAutoComplete, { membersBeforeSave } from 'ee_else_ce/gfm_auto_complete';
 
-import 'jquery.caret';
-import '@gitlab/at.js';
-
 import { TEST_HOST } from 'helpers/test_constants';
 import { getJSONFixture } from 'helpers/fixtures';