Support for network host_ipv4 label

[Fexiven]

Feature request description

Same as moby/moby#30053 & moby/libnetwork#2454

It should be possible to specify a host_ipv4 & host_ipv6 because currently the default route is used.

Suggest potential solution

Implement a way to let users specify either the interface or the IP address

Have you considered any alternatives?

The alternatives are custom ip routes, but having it built in would be way better

Additional context

No response

[Luap99]

This would need to be added to netavark first so I move the issue there.

I am not against it but adding support means supporting this for iptables/nftables and firewalld (WIP) so I am unlikely to work on that, AFAIK you can already add custom routes via out vrf support.