systemd: Add ability to define networks
systemd: Enable more network services
systemd-network: Add assertions for user clarity
nixos/network-interfaces: Provide a networkd implementation
nixos/network-interfaces-scripted: Fix network-setup triggering
networkd: Support Host Resolvconf
nixos/networking: Rebuild resolvconf during activation

This is needed when /etc/resolv.conf is being overriden by networkd
and other configurations. If the file is destroyed by an environment
activation then it must be rebuilt so that applications which interface
with /etc/resolv.conf directly don't break.
nixos/systemd: ip-up and network-online targets should come after networkd-wait-online
nixos: Support network-online target in addition to ip-up
nixos/network-interfaces: Support mac address and mtu universally
nixos/network-interfaces: Promote secondary addresses when primary addresses expire
nixos/dhcpcd: Respect per interface dhcp options
nixos/network-interfaces: Refactor scripts for reliability and dependency removal
nixos/network-interfaces: Make it clear that networkd is experimental
nixos/networking: Fixes
nixos/network-interfaces: Add maclvan support
nixos/network-interfaces: More fixes
nixos/tests: Add networking tests for basic functionality
Merge pull request #5043 from wkennington/master.networkd

nixos/networking: Revamp networking configuration and add an experimental networkd option.