RFC: ci: run tests in a container with systemd

The aim of this patch is to fix the failing pipeline for linux vdagent. The problem appeared with the addition of test-session-info.c as it tries to obtain info from systemd which is not running in the container.

I was searching for ways how to set up such environment. From what I've found, the container either needs to run in privileged mode (which probably isn't an option with GitLab), or you must make special adjustments, as described e.g. here. Again, I'm not sure whether it's possible with GitLab and I didn't find any guide/working setup.

The easiest option seems to be to use podman inside a regular container, which is what this patch does. The main issue is that all the packages are basically fetched twice - once inside the "main" container and once to build the image with systemd, so it takes some time.

Possible solution would be to use the GitLab container registry and rebuild the images once a week, for example, see https://gitlab.freedesktop.org/wayland/ci-templates.

However, I have doubts whether this is all worth it since the single test that fails is not very extensive, so it might be easier to just disable it. What do you think?

Signed-off-by: Jakub Janků jjanku@redhat.com