Configure RPMCI

This patch configures RPMCI so RPMs are built in Koji by GitLab jobs.

We can look at removing the RPMlint filters at a later stage.

The documentation patch to mig/manager-guide about the new e-group mig-build and the service account migbuild will follow when this is merged.

Please note that stable/qa tagging requires triggering the tagging jobs manually when a tag is pushed. It might be possible to override this by doing something like:

variables:
  AUTOTAG: 'True'
  AUTOTAG_QA: 'True'