Self-hosted CI runner with GPU

[LourensVeen]

Is your feature request related to a problem? Please describe.
The CI can't run any GPU tests because the free resources on GitHub don't have GPUs. Also getting MPI to work in there isn't easy. It would help if we set up a local machine in Leiden with a runner.

Describe the solution you'd like
A machine in Leiden that runs CI jobs, in a VM for security and in a Docker container for reproducibility. Try to make it robust and to minimise maintenance needs.

Describe alternatives you've considered
External hosting, but that's difficult to pay for. Easier to find an old machine with a GPU in it and spend time rather than money.

[LourensVeen]

@DavidJJansen set up a machine with an OS and access for me, so now we just need to install all the software. It's running RHEL 9, has 4 cores and 16 GB of RAM, and an nVidia Quattro T400 GPU.

For the VM, I think I'll do some kind of Red Hat-based OS too, Rocky or Alma, to keep things consistent and probably make it easier to map the GPU into the VM.

I've used Ansible before for setting up machines and liked it, and it's owned by Red Hat now so should integrate well. I also used Vagrant to make VMs then, but I did not like that and we don't have many VMs, so I'll stick with a shell script for (re)creating the VMs.

Then we probably need Docker and the GitHub runner software, and we need to integrate that with the rest and with the GitHub servers.