Port forward should be able to expose a port on a unix socket on the host

[guillaumerose]

Currently, only TCP port to TCP port forwarding is working. It would a great addition if a TCP port of the VM could be reachable on the host via an Unix socket.

Example usage:
Podman API can run on port 2375 and gvproxy can expose it as /var/run/docker.sock on the host.

[ghost]

Edit: Was simple to implement. Submitted PR #77

@guillaumerose, my PR needs a code review.

[ghost]

Updated PR to also support unix-to-unix over SSH.

This approach opens up the ability to have the podman machine completely accessible in the forwarder service. Perhaps refactoring to remove stuff like the ssh bastion code and gvproxy ssh forwarder can be considered.

[guillaumerose]

First part is merged (unix to tcp) #89

The second part is still WIP.