Internationalisation of javascript/s* directories

This is one of many MRs opened in order to improve the overall
internationalisation of the GitLab codebase.

i18n documentation
https://docs.gitlab.com/ee/development/i18n/externalization.html

app/assets/javascripts/sidebar/lib/sidebar_move_issue.js

 import $ from 'jquery';
 import _ from 'underscore';
+import { __ } from '~/locale';
 
 function isValidProjectId(id) {
   return id > 0;
@@ -40,7 +41,9 @@ class SidebarMoveIssue {
         this.mediator
           .fetchAutocompleteProjects(searchTerm)
           .then(callback)
-          .catch(() => new window.Flash('An error occurred while fetching projects autocomplete.'));
+          .catch(
+            () => new window.Flash(__('An error occurred while fetching projects autocomplete.')),
+          );
       },
       renderRow: project => `
         <li>
@@ -72,7 +75,7 @@ class SidebarMoveIssue {
       this.$confirmButton.disable().addClass('is-loading');
 
       this.mediator.moveIssue().catch(() => {
-        window.Flash('An error occurred while moving the issue.');
+        window.Flash(__('An error occurred while moving the issue.'));
         this.$confirmButton.enable().removeClass('is-loading');
       });
     }

app/assets/javascripts/sidebar/sidebar_mediator.js

@@ -2,6 +2,7 @@ import { visitUrl } from '../lib/utils/url_utility';
 import Flash from '../flash';
 import Service from './services/sidebar_service';
 import Store from './stores/sidebar_store';
+import { __ } from '~/locale';
 
 export default class SidebarMediator {
   constructor(options) {
@@ -45,7 +46,7 @@ export default class SidebarMediator {
       .then(data => {
         this.processFetchedData(data);
       })
-      .catch(() => new Flash('Error occurred when fetching sidebar data'));
+      .catch(() => new Flash(__('Error occurred when fetching sidebar data')));
   }
 
   processFetchedData(data) {

app/assets/javascripts/snippet/snippet_embed.js

+import { __ } from '~/locale';
+
 export default () => {
   const { protocol, host, pathname } = window.location;
   const shareBtn = document.querySelector('.js-share-btn');
@@ -10,7 +12,7 @@ export default () => {
     shareBtn.classList.add('is-active');
     embedBtn.classList.remove('is-active');
     snippetUrlArea.value = url;
-    embedAction.innerText = 'Share';
+    embedAction.innerText = __('Share');
   });
 
   embedBtn.addEventListener('click', () => {
@@ -18,6 +20,6 @@ export default () => {
     shareBtn.classList.remove('is-active');
     const scriptTag = `<script src="${url}.js"></script>`;
     snippetUrlArea.value = scriptTag;
-    embedAction.innerText = 'Embed';
+    embedAction.innerText = __('Embed');
   });
 };

locale/gitlab.pot

@@ -850,6 +850,9 @@ msgstr ""
 msgid "An error occurred while fetching markdown preview"
 msgstr ""
 
+msgid "An error occurred while fetching projects autocomplete."
+msgstr ""
+
 msgid "An error occurred while fetching sidebar data"
 msgstr ""
 
@@ -895,6 +898,9 @@ msgstr ""
 msgid "An error occurred while making the request."
 msgstr ""
 
+msgid "An error occurred while moving the issue."
+msgstr ""
+
 msgid "An error occurred while parsing recent searches"
 msgstr ""
 
@@ -3872,6 +3878,9 @@ msgstr ""
 msgid "Error loading viewer"
 msgstr ""
 
+msgid "Error occurred when fetching sidebar data"
+msgstr ""
+
 msgid "Error occurred when toggling the notification subscription"
 msgstr ""