migrate projects:tags:new to static bundle

app/assets/javascripts/dispatcher.js

@@ -53,11 +53,6 @@ var Dispatcher;
         case 'projects:merge_requests:edit':
           shortcut_handler = true;
           break;
-        case 'projects:tags:new':
-          import('./pages/projects/tags/new')
-            .then(callDefault)
-            .catch(fail);
-          break;
         case 'projects:services:edit':
           import('./pages/projects/services/edit')
             .then(callDefault)

app/assets/javascripts/pages/projects/tags/new/index.js

@@ -2,8 +2,8 @@ import RefSelectDropdown from '../../../../ref_select_dropdown';
 import ZenMode from '../../../../zen_mode';
 import GLForm from '../../../../gl_form';
 
-export default () => {
+document.addEventListener('DOMContentLoaded', () => {
   new ZenMode(); // eslint-disable-line no-new
   new GLForm($('.tag-form'), true); // eslint-disable-line no-new
   new RefSelectDropdown($('.js-branch-select')); // eslint-disable-line no-new
-};
+});