Add SELinux rule for gel-server RHEL/CentOS packages

[fmoor]

On CentOS with CELinux enabled the gel-server systemd service fails with:

Feb 28 18:01:31 fmoor-guide-centos edgedb-server[19154]: CRITICAL 19154 - 2025-02-28T18:01:31.466 edb.server: cannot write to the runstate directory: [Errno 13] Permission denied: '/run/edgedb/.s.GEL.admin.5656' -> '/run/edgedb/.s.EDGEDB.admin.5656'; please fix the permissions or use --runstate-dir to specify the correct location

Disabling SELinux resolves the error. The gel-server package should ship with an SELinux rule that allows access to the runstate directory and possibly others.