Provide a systemd for the xDAQ jobcontrol daemon

Summary

At the moment, there is no official xDAQ zone for GEM. Requesting and creating one is a burden for multiple reasons:

• The xDAQ zones are centrally an externally managed.
• First-grade support is provided only for b904 and p5 operations.
• Documentation is poor or absent.
• Only the jobcontrol service is being used.

Considering this, one could produce a simple systemd unit starting directly and only the jobcontrol daemon.

What is the expected correct behavior?

A systemd unit starting the xDAQ jobcontrol daemon is provided in its own RPM package.