Wired network management

Spun off from https://github.com/helloSystem/Menu/issues/23#issuecomment-765926726

Need a GUI for when:

* network connection with DHCP is not automated
* static addressing is required.

### Example (DHCP)

1. Start the system offline
2. make a wired connection to a DHCP network

– there's no interface to the connection.

Need to create the interface, and so on.

### Reference

* https://www.freebsd.org/cgi/man.cgi?query=ifconfig(8)
* https://www.freebsd.org/cgi/man.cgi?query=re(4)
* https://www.freebsd.org/cgi/man.cgi?query=resolvconf(8)
* https://www.freebsd.org/cgi/man.cgi?query=route(8)
* et cetera.

### Thoughts

I shouldn't recommend writing an app from scratch (thin end of a wedge).

Instead, seek an existing app. Ideally one that can integrate with the global menu, although I don't view https://github.com/helloSystem/Menu as a strict requirement; an app amongst utilities should suffice.