That library didn't do it for me.
Adding async methods was a pain in the a** with lifetime and type bounds
confusing the heck out of me.
So I tried it with `dbus::tree` (in the next commits). It still was a
bit of work to get it working, but at least it **is** working.
The unit file is only for debugging purposes.
The Makefile is used to install (link --runtime), start, stop, and
restart the service, and to see the output (journalctl)
...because apparently it's not allowed to have dependencies in the
workspace manifest if it only defines other members and isn't a member
itself or something 🤷♂️
