Extend job policy for forks

Background:

For ee_compat_check job, we don't want to run it for any of the EE repositories. However, we can only specify project full path, not project name. An alternative way to do this, would be allowing control over forks. Something like:

job:
  except:
    - forks@gitlab-org/gitlab-ee
    - branches@gitlab-org/gitlab-ee
    - tags@gitlab-org/gitlab-ee

The downside of this is that, in order to check this, we'll need to query the project in order to figure out if it's forked from there or not.

If we just allow checking the name, we don't need to do this. However we'll need to think more carefully about the syntax to specify this.

Reference:

The following discussion from gitlab-ce!14189 should be addressed:

• @rymai commented on a discussion: (+3 comments)

  Is there a way to exclude all gitlab-ee repos regardless of the namespace? 🤔