Remember post preview tab when switching between preview/publish

refs https://github.com/TryGhost/Team/issues/1621

- added `currentTab` and `changeTab()` data arguments to preview modal allowing for the current tab to be remembered across opens in the `<PublishManagement>` component that controls open/close of the preview modal

ghost/admin/app/components/editor-labs/modals/preview.js

@@ -14,7 +14,7 @@ export default class EditorPostPreviewModal extends Component {
         ignoreBackdropClick: true
     };
 
-    @tracked tab = 'browser';
+    @tracked tab = this.args.data.currentTab || 'browser';
 
     constructor() {
         super(...arguments);
@@ -24,6 +24,7 @@ export default class EditorPostPreviewModal extends Component {
     @action
     changeTab(tab) {
         this.tab = tab;
+        this.args.data.changeTab?.(tab);
     }
 
     @task

ghost/admin/app/components/editor-labs/publish-management.js

@@ -9,6 +9,7 @@ import {action} from '@ember/object';
 import {capitalize} from '@ember/string';
 import {inject as service} from '@ember/service';
 import {task, taskGroup, timeout} from 'ember-concurrency';
+import {tracked} from '@glimmer/tracking';
 import {use} from 'ember-could-get-used-to-this';
 
 const SHOW_SAVE_STATUS_DURATION = 3000;
@@ -26,6 +27,8 @@ export default class PublishManagement extends Component {
     // ensure we get a new PublishOptions instance when @post is replaced
     @use publishOptions = new PublishOptionsResource(() => [this.args.post]);
 
+    @tracked previewTab = 'browser';
+
     publishFlowModal = null;
     updateFlowModal = null;
 
@@ -88,11 +91,18 @@ export default class PublishManagement extends Component {
                 post: this.publishOptions.post,
                 hasDirtyAttributes: this.args.hasUnsavedChanges,
                 saveTask: this.saveTask,
-                togglePreviewPublish: this.togglePreviewPublish
+                togglePreviewPublish: this.togglePreviewPublish,
+                currentTab: this.previewTab,
+                changeTab: this.changePreviewTab
             });
         }
     }
 
+    @action
+    changePreviewTab(tab) {
+        this.previewTab = tab;
+    }
+
     @action
     async togglePreviewPublish(event) {
         event?.preventDefault();