Inconsistent `Transport` API for UDP server

[dragonhunt02]

I'm trying to use Transport:controlling_process(Sock, NewPid) inside process spawned by esockd:open(..., MFArgs), but it fails when using UDP with badarg. Sock argument is from

esockd/examples/udp/udp_echo_server.erl

Lines 34 to 35 in d0c3edc

	loop(Transport = {udp, Server, Sock}, Peer = {IP, Port}) ->
	receive

It seems that gen_udp:controlling_process is not implemented.

esockd/src/esockd_transport.erl

Lines 89 to 96 in d0c3edc

	-spec(controlling_process(socket(), pid()) -> ok | {error, Reason} when
	Reason :: closed | not_owner | badarg | inet:posix()).
	controlling_process(Sock, NewOwner) when is_port(Sock) ->
	gen_tcp:controlling_process(Sock, NewOwner);
	controlling_process(#ssl_socket{ssl = SslSock}, NewOwner) ->
	ssl:controlling_process(SslSock, NewOwner);
	controlling_process(#proxy_socket{socket = Sock}, NewOwner) ->
	controlling_process(Sock, NewOwner);

I can't simply use gen_udp:controlling_process() as workaround since socket is in a different process (error current process is not the owner of the socket)

I think we could fix it by updating the Pid assigned to a Peer with an exported function.

esockd/src/esockd_udp.erl

Lines 273 to 278 in d0c3edc

	handle_info({udp, Sock, IP, InPortNo, Packet},
	State = #state{sock = Sock, peers = Peers, access_rules = Rules}) ->
	case maps:find(Peer = {IP, InPortNo}, Peers) of
	{ok, Pid} ->
	Pid ! {datagram, self(), Packet},
	{noreply, State};