Function stunclient::just_give_me_the_udp_socket_and_its_external_address

pub fn just_give_me_the_udp_socket_and_its_external_address(
) -> (UdpSocket, SocketAddr)

Super-simple function with everything hard coded: just return UdpSocket and its external address in one step May block, may panic, uses public Google STUN server.