✨(backend) use room_create grant for room auto creation

This patch sets the room_create grant for room admins,
allowing livekit's global room auto create option to be
disabled.

Author: networkException

src/backend/core/utils.py

@@ -90,6 +90,7 @@ def generate_token(
         room=room,
         room_join=True,
         room_admin=is_admin_or_owner,
+        room_create=is_admin_or_owner,
         can_update_own_metadata=True,
         can_publish=bool(sources),
         can_publish_sources=sources,