Refactored use of ShortcutsRoute mixin on editor 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/editor.js

@@ -247,6 +247,16 @@ export default Controller.extend({
             this.toggleProperty('showEmailPreviewModal');
         },
 
+        openPostPreview(keyboardEvent) {
+            keyboardEvent?.preventDefault();
+
+            if (this.post.isDraft) {
+                this.send('openPostPreviewModal');
+            } else {
+                window.open(this.post.previewUrl, '_blank', 'noopener');
+            }
+        },
+
         openPostPreviewModal() {
             this.modals.open('modals/post-preview', {
                 post: this.post,

ghost/admin/app/routes/editor.js

@@ -1,22 +1,16 @@
 import $ from 'jquery';
 import AuthenticatedRoute from 'ghost-admin/routes/authenticated';
-import ShortcutsRoute from 'ghost-admin/mixins/shortcuts-route';
-import ctrlOrCmd from 'ghost-admin/utils/ctrl-or-cmd';
 import {htmlSafe} from '@ember/template';
 import {run} from '@ember/runloop';
 import {inject as service} from '@ember/service';
 
-let generalShortcuts = {};
-generalShortcuts[`${ctrlOrCmd}+p`] = 'preview';
-
-export default AuthenticatedRoute.extend(ShortcutsRoute, {
+export default AuthenticatedRoute.extend({
     feature: service(),
     notifications: service(),
     userAgent: service(),
     ui: service(),
 
     classNames: ['editor'],
-    shortcuts: generalShortcuts,
 
     activate() {
         this._super(...arguments);
@@ -47,14 +41,6 @@ export default AuthenticatedRoute.extend(ShortcutsRoute, {
             });
         },
 
-        preview() {
-            if (this.controller.post.isDraft) {
-                this.controller.send('openPostPreviewModal');
-            } else {
-                window.open(this.controller.post.previewUrl, '_blank', 'noopener');
-            }
-        },
-
         authorizationFailed() {
             this.controller.send('toggleReAuthenticateModal');
         },

ghost/admin/app/templates/editor.hbs

@@ -1,5 +1,5 @@
 {{#if this.post}}
-    <div class="flex flex-row">
+    <div class="flex flex-row" {{on-key "cmd+p" (action "openPostPreview")}}>
         <GhEditor
             @tagName="section"
             @class="gh-editor gh-view relative"