Add Vue and GitLab Ui boilerplate code

- Add global translations in Vue templates
- Add init code for GitLab UI to the Jira Connect entry point
- Add use of feature flags in the app
- Add CSS used by GitLab UI for Boostrap and utilities

app/assets/javascripts/jira_connect/index.js

 import Vue from 'vue';
 import $ from 'jquery';
+import setConfigs from '@gitlab/ui/dist/config';
+import Translate from '~/vue_shared/translate';
+import GlFeatureFlagsPlugin from '~/vue_shared/gl_feature_flags_plugin';
+
 import App from './components/app.vue';
 
 const store = {
@@ -75,6 +79,14 @@ function initJiraConnect() {
 
   initJiraFormHandlers();
 
+  if (!el) {
+    return null;
+  }
+
+  setConfigs();
+  Vue.use(Translate);
+  Vue.use(GlFeatureFlagsPlugin);
+
   return new Vue({
     el,
     data: {

app/assets/stylesheets/page_bundles/jira_connect.scss

@@ -2,6 +2,11 @@
 // We should only import styles that we actually use.
 // @import '@gitlab/ui/src/scss/gitlab_ui';
 
+@import '@gitlab/ui/src/scss/bootstrap';
+@import 'bootstrap-vue/src/index';
+
+@import '@gitlab/ui/src/scss/utilities';
+
 $atlaskit-border-color: #dfe1e6;
 
 .ac-content {