https://github.com/vyos/vyos-1x/pull/2481 added a bunch of new smoketests.

While debugging those failing, it was uncovered, that uvicorn only listens on IPv4 connections

vyos@vyos# netstat -tulnp | grep 8080
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 127.0.0.1:8080          0.0.0.0:*               LISTEN      -

As the CLI already has an option to move the API communication from an IP socket to a UNIX domain socket, the best idea is to make this the default way of communication, as we never directly talk to the API server but rather use the NGINX reverse proxy.

Migrate the CLI to and always use the socket CLI option
Rename listen-port from virtual-host to port to be consistent with other CLI components