WIP: Building testable containers in the Gitlab CI
This is a WIP series, based on https://gitlab.freedesktop.org/mupuf/valve-infra/-/merge_requests/40 which is waiting on review.
It contains the scripts to build a testing container from the Mesa CI, eventually these scripts should be in the Mesa repo, but it takes a very long time to test changes in that project, since you need to wait for a full CI pipeline to run a radv job, by side-loading them in the runner container, I make a change, push the container, and retry the job. 20 minutes vs 20 seconds this way.