Use unix socket for pubsub for mac/linux and fallback to loopback address on windows or at least support unix socket.

[fcevado]

using UDS would avoid relying on network stack.
on elixir side :gen_tcp works with UDS, so it's just a matter on changing configs.
on rust side afaik, it would be required to use UnixStream/UnixListener instead of TcpStream/TcpListener.

even if it's not the default way to connect the pubsub, at least it would be good support it.