This commit extends our `coreos-home-server-update` script with support
for updating host directories with configuration collected across
multiple remote directories of the same name. This will, essentially,
allow for extending systemd services with custom configuration, as
sometimes required of base systemd service files.
This commit removes host configuration that is only useful for my own
personal use-cases, and leaves base and virtual hosts, which are more
commonly useful. It is intended that additional hosts are tracked as
either submodules or subtrees, as required by individual use-cases.
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.