Add support for multiple unix socket forwards over ssh

[n1hility]

This PR extends the unix socket forwarding capability to support multiple socket forwards.

The use-case to extend this to multiple sockets is that podman machine may wish to expose both rootful and rootless ports similar to the original prototype. It follows the same convention as the --listen endpoint for consistency.

Note: To keep the concurrency model simple, it utilizes multiple ssh connections, one per unix socket. Since this is all multiplexed over vsock there isn't much of an advantage to muxing over a single ssh connection anyway.

[openshift-ci]

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[n1hility]

/cc @guillaumerose

[guillaumerose]

lgtm, thanks!

[guillaumerose]

Let me know when you need a release @baude @n1hility

You can do brew install podman --head also. It will take podman main branch and this repo main branch.

[gbraad]

This is a possible breaking change of the API. How does this affect consumers?

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Gvproxy only, though the tests are defined as generic