And introduce a `purge` target, intended to supplant the current `clean`
target, in allowing the latter to be used to clean Butane configuration
without removing any cached images.
This commit represents a large amount of work toward moving services to
a more standard approach to storing data, and a simplification in how
networks are managed.
This will help make subsequent synchronization with hosts easier, as
systemd files and potential dropins are guarnateed to exist under a
certain hierarchy that can be dropped as-is into host configuration
directories.
This contains the culmination of work done privately for a few months,
and is intended to be a solid basis for other peoples' experimentations
with setting up single-node, home-server setups using Fedora CoreOS.
