Actually lazy load swagger ui (#7067)

* switch to dynamic imports so that bundling doesn't include swagger-ui-dist in its vendor file

* remove ember-ajax

* delete comment

* update comment about lazy loading in the engine index.js

ui/.eslintrc.js

@@ -1,4 +1,5 @@
 module.exports = {
+  parser: 'babel-eslint',
   root: true,
   parserOptions: {
     ecmaVersion: 2018,