Update nw script to new iwd based setup

[eikenb]

I've switched my wifi network setup to use iwd + systemd-networkd instead of ifupdown + wpa_supplicant + dhcpcd + resolvconf. Much simpler, tons faster at connecting, and other niceties. As I still am using the command line to run it I think there are parts that could be scripted and I figure I'll just convert my old nw script as I've used it enough to remember it.