Function remote_room_summary_hierarchy_response 

async fn remote_room_summary_hierarchy_response(
    services: &Services,
    room_id: &RoomId,
    servers: &[OwnedServerName],
    sender_user: Option<&UserId>,
) -> Result<SpaceHierarchyParentSummary>

used by MSC3266 to fetch a room’s info if we do not know about it