✨(backend) allow LiveKit users to update their own metadata

This is required, if users need to update their names, or participant
information.

src/backend/core/utils.py

@@ -26,6 +26,7 @@ def generate_token(room: str, user, username: Optional[str] = None) -> str:
     video_grants = VideoGrants(
         room=room,
         room_join=True,
+        can_update_own_metadata=True,
         can_publish_sources=[
             "camera",
             "microphone",