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.
Container volume backup logic has been moved to a (largely equivalent)
external script, allowing for future expansion of functionality. In
addition, a `rclone-pull@` service has been added and set up as a default
dependency for the `container-volume-restore@` service, allowing for
automatic set up of servers based on latest remote backups.
This commit contains a fairly large diff for a fairly small change:
moving the `config/common` directory to `host/base` to better reflect
its intended use, and promoting `config/service` to the root directory.
These changes unlock some improvements in `coreos-home-server-update`
processes, which will (assuming `/etc/coreos-home-server/base` exists)
keep host-wide systemd services in sync in addition to service-specific
ones.
Changes have been make to the `Makefile` and a few other places where
`config/common` was referenced, but most of this work is renames that
are not intended to break compatibility with new or running servers.
