Set up Cirrus CI to test on Fedora

[kolyshkin]

Since GHA only supports Ubuntu Linux, which does not come with SELinux enabled, CI setup for this repository is currently useless (see here or here.

I propose to add .cirrus.yml and run some tests on RHEL clones (and, maybe, Fedora), as they come with SELinux already configured.

We need some help configuring Cirrus CI integration for this repo.

(will add more details later, consider this a draft for now)

[kolyshkin]

So, what we need here is to enable Cirrus CI for this repo. I don't have the rights to do it. @caniszczyk @amye please halp.