Add option to forward arbitrary ports

[cgwalters]

https://gitlab.com/bootc-org/podman-bootc-cli/-/issues/14

Currently, port 22 is automatically forwarded to a random port to enable ssh access. I imagine some users will have a container image that starts a web service that they will want to verify is running. This will require forwarding some arbitrary port (e.g. 8080) to enable local access.