Support MSC4143 RTC Transport endpoint (#3629)

* Use rtc-focus branch of js-sdk

* Update makeTransport to fetch backend transports and validate all transports before response.

* Fix test

* Add test

* Loads more tests

* Add tests for openid errors

* improve comment

* update to develop commit

* Add JWT parsing

* Use JWT

* Cleanup

* fixup tests

* fixup tests

* lint

* lint lint

* Fix `Reconnecting`

playwright/fixtures/jwt-token.ts

@@ -0,0 +1,22 @@
+/*
+Copyright 2025 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE in the repository root for full details.
+*/
+
+export function createJTWToken(sub: string, room: string): string {
+  return [
+    {}, // header
+    {
+      // payload
+      sub,
+      video: {
+        room,
+      },
+    },
+    {}, // signature
+  ]
+    .map((d) => global.btoa(JSON.stringify(d)))
+    .join(".");
+}