Refactored use of ShortcutsRoute mixin on tags screen

no issue

- mixins are deprecated in Ember so we want to remove their usage
  - pre-requisite for easier automation for switching to native class syntax
- removed ShortcutsRoute mixin in favor of using the `{{on-key}}` modifier and standard controller action

ghost/admin/app/controllers/tags.js

@@ -1,8 +1,10 @@
 import Controller from '@ember/controller';
 import {alias, sort} from '@ember/object/computed';
 import {computed} from '@ember/object';
+import {inject as service} from '@ember/service';
 
 export default Controller.extend({
+    router: service(),
 
     queryParams: ['type'],
     type: 'public',
@@ -24,6 +26,10 @@ export default Controller.extend({
     actions: {
         changeType(type) {
             this.set('type', type);
+        },
+
+        newTag() {
+            this.router.transitionTo('tag.new');
         }
     }
 });

ghost/admin/app/routes/tags.js

@@ -1,7 +1,6 @@
 import AuthenticatedRoute from 'ghost-admin/routes/authenticated';
-import ShortcutsRoute from 'ghost-admin/mixins/shortcuts-route';
 
-export default AuthenticatedRoute.extend(ShortcutsRoute, {
+export default AuthenticatedRoute.extend({
     queryParams: {
         type: {
             refreshModel: true,
@@ -9,15 +8,6 @@ export default AuthenticatedRoute.extend(ShortcutsRoute, {
         }
     },
 
-    shortcuts: null,
-
-    init() {
-        this._super(...arguments);
-        this.shortcuts = {
-            c: 'newTag'
-        };
-    },
-
     // authors aren't allowed to manage tags
     beforeModel() {
         this._super(...arguments);
@@ -40,12 +30,6 @@ export default AuthenticatedRoute.extend(ShortcutsRoute, {
         }
     },
 
-    actions: {
-        newTag() {
-            this.transitionTo('tag.new');
-        }
-    },
-
     buildRouteInfoMetadata() {
         return {
             titleToken: 'Tags'

ghost/admin/app/templates/tags.hbs

@@ -1,4 +1,4 @@
-<section class="gh-canvas">
+<section class="gh-canvas" {{on-key "c" (action "newTag")}}>
     <GhCanvasHeader class="gh-canvas-header">
         <h2 class="gh-canvas-title" data-test-screen-title>Tags</h2>
         <section class="view-actions">