Add unit files to manage services with systemd

Description

Now that we're on EL9, I think we can simplify how we manage calibration services by using user-level systemd. This adds unit files for the 3 services. It will also need changes to the deployment machinery to install these files & start the services.

How Has This Been Tested?

TBD

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the code style of this project.

Reviewers

@roscar @schmidtp

webservice/systemd/cal-job-monitor.service

 [Unit]
 Description=XFEL offline calibration Slurm job monitor
+PartOf=cal-services.target
 
 [Service]
 Type=exec
@@ -8,4 +9,4 @@ ExecStart=%h/deployments/development/git.xfel.eu/detectors/pycalibration/current
 Restart=on-failure
 
 [Install]
-WantedBy=default.target
+WantedBy=cal-services.target