Cleanup network configure

1. install_arch supports both DHCP and static networking
2. common only supports static networking
3. install_arch always enable systemd-resolved
4. common only enables systemd-resolved if a local recursive resolver isn't configured
5. If static networking is configured but no dns_servers is provided systemd-resolveduse the fallback DNS servers
6. monitoring.archlinux.org is configured with both DHCP and static networking

In other words: it is a mess..

Idea: We should move the network logic to its own role and include that role in install_arch and common.

We can also look at the device type instead of the name, as archiso is doing: archiso@8a521d0b