Add support for `l`, `e` and `r` keyboard shortcuts in Epic

ee/app/assets/javascripts/behaviors/shortcuts/shortcuts_epic.js

+import $ from 'jquery';
+import Mousetrap from 'mousetrap';
+import Cookies from 'js-cookie';
+import ShortcutsIssuable from '~/behaviors/shortcuts/shortcuts_issuable';
+
+export default class ShortcutsEpic extends ShortcutsIssuable {
+  constructor() {
+    super();
+
+    const $issuableSidebar = $('.js-issuable-update');
+
+    Mousetrap.bind('l', () =>
+      ShortcutsEpic.openSidebarDropdown($issuableSidebar.find('.js-labels-block')),
+    );
+    Mousetrap.bind('r', ShortcutsIssuable.replyWithSelectedText);
+    Mousetrap.bind('e', ShortcutsIssuable.editIssue);
+  }
+
+  static openSidebarDropdown($block) {
+    if (Cookies.get('collapsed_gutter') === 'true') {
+      document.dispatchEvent(new Event('toggleSidebarRevealLabelsDropdown'));
+    } else {
+      $block.find('.js-sidebar-dropdown-toggle').trigger('click');
+    }
+  }
+}

ee/app/assets/javascripts/epics/sidebar/components/sidebar_app.vue

@@ -226,9 +226,17 @@ export default {
   },
   mounted() {
     eventHub.$on('toggleSidebar', this.toggleSidebar);
+    document.addEventListener(
+      'toggleSidebarRevealLabelsDropdown',
+      this.toggleSidebarRevealLabelsDropdown,
+    );
   },
   beforeDestroy() {
     eventHub.$off('toggleSidebar', this.toggleSidebar);
+    document.removeEventListener(
+      'toggleSidebarRevealLabelsDropdown',
+      this.toggleSidebarRevealLabelsDropdown,
+    );
   },
   methods: {
     getDateValidity(startDate, endDate) {

ee/app/assets/javascripts/pages/groups/epics/show/index.js

 import ZenMode from '~/zen_mode';
 import initEpicShow from 'ee/epics/epic_show/epic_show_bundle';
+import ShortcutsEpic from 'ee/behaviors/shortcuts/shortcuts_epic';
 import '~/notes/index';
 
 document.addEventListener('DOMContentLoaded', () => {
   new ZenMode(); // eslint-disable-line no-new
   initEpicShow();
+  new ShortcutsEpic(); // eslint-disable-line no-new
 });