Playwright test for dehydrated devices with MAS (#34095)

* Device dehydration tests: use common util for recovery setup

We have a utility method for setting up the recovery key, so let's use it.

* Factor out shared method for creating encrypted rooms

* Playwright test for device dehydration

Add a playwright test to check that this stuff actually works.

* Factor out `verifyAfterLogin` as a separate function

* Playwright test for dehydrated devices with MAS

apps/web/playwright/e2e/crypto/event-shields.spec.ts

@@ -14,9 +14,10 @@ import {
     createSecondBotDevice,
     createSharedEncryptedRoomWithUser,
     enableKeyBackup,
-    logIntoElementAndVerify,
+    logIntoElement,
     logOutOfElement,
     verify,
+    verifyAfterLogin,
     waitForDevices,
 } from "./utils";
 import { bootstrapCrossSigningForClient } from "../../pages/client.ts";
@@ -170,7 +171,8 @@ test.describe("Cryptography", function () {
                     window.localStorage.clear();
                 });
                 await page.reload();
-                await logIntoElementAndVerify(page, aliceCredentials, securityKey);
+                await logIntoElement(page, aliceCredentials);
+                await verifyAfterLogin(page, securityKey);
 
                 /* go back to the test room and find Bob's message again */
                 await app.viewRoomById(testRoomId);