WIP Move to Holy Build Box

[lenary]

This is the move suggested in #21. Hopefully it is this easy, but I doubt it.

[lenary]

Ok, so the main thing broken here is that we don't have sudo, so we cannot use yum to install anything… which is a little vexing, tbh. It looks like the solution is to add a Dockerfile, so we build the container (based off the holy-build-box-64:latest image), and then run inside the container. Nightmare, but it might help get rid of the _build_deps.yml file we have.

[lenary]

Closing in favour of #39, because Azure won't push to github packages unless the PR comes from the same repo.

It might just be a better idea to move this all to github actions, but that could cause other issues so I'm wary of doing so.