Adding tests

This MR spawns a VM, makes sure it runs the required kernel that matches the kmod package, and follows http://linux.web.cern.ch/linux/centos8/docs/afs.shtml for testing AFS using this just built package.

I took the liberty of adding extra comments as it is not obvious how we play with variables for two totally different pipelines, even if README mentions it

Thanks to Alex and Dani for helping with this as well.