Support Unix domain socket (UDS) path connections #7

This project currently has a focus on creating TCP/IP-based connections. Additionally, we should provide a way to connect to a remote server that is listening on a Unix domain socket (UDS) path. For example, this is a common setup when using databases (MySQL etc.). We may be able to use the ssh -L option which also supports Unix socket paths in recent OpenSSH versions (unlike the -W and -D options).