Move internal CI manifest to nonfree

[sermazz]

This PR moves the internal GitLab CI manifest to the nonfree component, for easier future usage with proprietary tools. It works by launching a pipeline in the internal repo https://iis-git.ee.ethz.ch/github-mirror/chimera. Within this, the repo https://iis-git.ee.ethz.ch/pulp-restricted/chimera-nonfree is cloned and the CI subpipe contained there is spawned. This streamlines the usage of scripts for licensed tools and technology files, which will all be contained in chimera-nonfree. This PR also addresses the comments in https://github.com/pulp-platform/chimera/pull/14.

[sermazz]

I addressed your review :) Just for completeness, I list here the required changes in the other repositories:

• https://iis-git.ee.ethz.ch/pulp-restricted/chimera-nonfree: I created a deploy tag which is cloned instead of the commit hash; also added a readme to explain its usage
• https://iis-git.ee.ethz.ch/github-mirror/chimera: I changed the path of the CI to execute to .gitlab/gitlab-ci.yml, as I created this new directory to also hold nonfree-var.yml and keep stuff tidy. The internal CI might not work anymore for branches which do not include the commits in this PR

[Scheremo]

I addressed your review :) Just for completeness, I list here the required changes in the other repositories:

* https://iis-git.ee.ethz.ch/pulp-restricted/chimera-nonfree: I created a `deploy` tag which is cloned instead of the commit hash; also added a readme to explain its usage

* https://iis-git.ee.ethz.ch/github-mirror/chimera: I changed the path of the CI to execute to `.gitlab/gitlab-ci.yml`, as I created this new directory to also hold `nonfree-var.yml` and keep stuff tidy. The internal CI might not work anymore for branches which do not include the commits in this PR

Looks good to me! Thanks for the support for test additions in the main repo.