Function device_response 

pub(super) fn device_response(
    device: Device,
    user_id: &UserId,
    dehydrated: Option<&DeviceId>,
) -> Device

Map a stored device into the admin API wire shape. Tuwunel keeps no user-agent, so last_seen_user_agent is always absent; dehydrated is present on every device only when the owner has a dehydrated one.