fix(accessibility): tab support at login, reset and signup pages, buttons at ATE and app bar (#24214)

e2e-tests/playwright/support/ui/components/main_header.ts

@@ -0,0 +1,24 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+import {expect, Locator} from '@playwright/test';
+
+export default class MainHeader {
+    readonly container: Locator;
+
+    readonly logo;
+    readonly backButton;
+
+    constructor(container: Locator) {
+        this.container = container;
+
+        this.logo = container.locator('.header-logo-link');
+        this.backButton = container.getByTestId('back_button');
+    }
+
+    async toBeVisible() {
+        await expect(this.container).toBeVisible();
+    }
+}
+
+export {MainHeader};