Move EE specific GfmAutocomplete code to EE file

Refactor GfmAutocomplete and create a new EE counterpart
which is referenced through `ee_else_ce`

app/assets/javascripts/behaviors/markdown/gfm_auto_complete.js

 import $ from 'jquery';
 import { parseBoolean } from '~/lib/utils/common_utils';
-import GfmAutoComplete from '~/gfm_auto_complete';
+import GfmAutoComplete from 'ee_else_ce/gfm_auto_complete';
 
 export default function initGFMInput() {
   $('.js-gfm-input:not(.js-vue-textarea)').each((i, el) => {

app/assets/javascripts/gl_form.js

 import $ from 'jquery';
 import autosize from 'autosize';
-import GfmAutoComplete, * as GFMConfig from './gfm_auto_complete';
+import GfmAutoComplete, { defaultAutocompleteConfig } from 'ee_else_ce/gfm_auto_complete';
 import dropzoneInput from './dropzone_input';
 import { addMarkdownListeners, removeMarkdownListeners } from './lib/utils/text_markdown';
 
@@ -8,7 +8,7 @@ export default class GLForm {
   constructor(form, enableGFM = {}) {
     this.form = form;
     this.textarea = this.form.find('textarea.js-gfm-input');
-    this.enableGFM = Object.assign({}, GFMConfig.defaultAutocompleteConfig, enableGFM);
+    this.enableGFM = Object.assign({}, defaultAutocompleteConfig, enableGFM);
     // Disable autocomplete for keywords which do not have dataSources available
     const dataSources = (gl.GfmAutoComplete && gl.GfmAutoComplete.dataSources) || {};
     Object.keys(this.enableGFM).forEach(item => {

app/assets/javascripts/issuable_form.js

 import $ from 'jquery';
 import Pikaday from 'pikaday';
+import GfmAutoComplete from 'ee_else_ce/gfm_auto_complete';
 import Autosave from './autosave';
 import UsersSelect from './users_select';
-import GfmAutoComplete from './gfm_auto_complete';
 import ZenMode from './zen_mode';
 import AutoWidthDropdownSelect from './issuable/auto_width_dropdown_select';
 import { parsePikadayDate, pikadayToString } from './lib/utils/datetime_utility';

app/assets/javascripts/pages/profiles/show/index.js

 import $ from 'jquery';
 import createFlash from '~/flash';
-import GfmAutoComplete from '~/gfm_auto_complete';
+import GfmAutoComplete from 'ee_else_ce/gfm_auto_complete';
 import emojiRegex from 'emoji-regex';
 import EmojiMenu from './emoji_menu';
 

app/assets/javascripts/set_status_modal/set_status_modal_wrapper.vue

@@ -2,7 +2,7 @@
 import $ from 'jquery';
 import createFlash from '~/flash';
 import Icon from '~/vue_shared/components/icon.vue';
-import GfmAutoComplete from '~/gfm_auto_complete';
+import GfmAutoComplete from 'ee_else_ce/gfm_auto_complete';
 import { __, s__ } from '~/locale';
 import Api from '~/api';
 import { GlModal, GlTooltipDirective } from '@gitlab/ui';

spec/frontend/gfm_auto_complete_spec.js

 /* eslint no-param-reassign: "off" */
 
 import $ from 'jquery';
-import GfmAutoComplete from '~/gfm_auto_complete';
+import GfmAutoComplete from 'ee_else_ce/gfm_auto_complete';
 
 import 'jquery.caret';
 import 'at.js';