I18N JS files starting with s

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

This commit only targets Vanilla JS files.

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

app/assets/javascripts/search_autocomplete.js

@@ -2,7 +2,7 @@
 
 import $ from 'jquery';
 import { escape, throttle } from 'underscore';
-import { s__, sprintf } from '~/locale';
+import { s__, __, sprintf } from '~/locale';
 import { getIdenticonBackgroundClass, getIdenticonTitle } from '~/helpers/avatar_helper';
 import axios from './lib/utils/axios_utils';
 import DropdownUtils from './filtered_search/dropdown_utils';
@@ -439,7 +439,7 @@ export class SearchAutocomplete {
 
   restoreMenu() {
     var html;
-    html = '<ul><li class="dropdown-menu-empty-item"><a>Loading...</a></li></ul>';
+    html = `<ul><li class="dropdown-menu-empty-item"><a>${__('Loading...')}</a></li></ul>`;
     return this.dropdownContent.html(html);
   }
 

app/assets/javascripts/star.js

@@ -31,7 +31,7 @@ export default class Star {
             $this.prepend(spriteIcon('star', iconClasses));
           }
         })
-        .catch(() => Flash('Star toggle failed. Try again later.'));
+        .catch(() => Flash(__('Star toggle failed. Try again later.')));
     });
   }
 }

app/assets/javascripts/subscription_select.js

 import $ from 'jquery';
+import { __ } from './locale';
 
 export default function subscriptionSelect() {
   $('.js-subscription-event').each((i, element) => {
@@ -8,7 +9,7 @@ export default function subscriptionSelect() {
       selectable: true,
       fieldName,
       toggleLabel(selected, el, instance) {
-        let label = 'Subscription';
+        let label = __('Subscription');
         const $item = instance.dropdown.find('.is-active');
         if ($item.length) {
           label = $item.text();

locale/gitlab.pot

@@ -9056,6 +9056,9 @@ msgstr ""
 msgid "Star a label to make it a priority label. Order the prioritized labels to change their relative priority, by dragging."
 msgstr ""
 
+msgid "Star toggle failed. Try again later."
+msgstr ""
+
 msgid "StarProject|Star"
 msgstr ""
 
@@ -9188,6 +9191,9 @@ msgstr ""
 msgid "Subscribed"
 msgstr ""
 
+msgid "Subscription"
+msgstr ""
+
 msgid "Subtracts"
 msgstr ""