Move the test into a role
    
    So that it can be called from the container-tools module without
    duplication. For technical reasons this requires calling the test entry
    script from a different directory, so parameterize it.
    
    Rename the test from "browser" to "cockpit-podman" so that it is
    more descriptive within a module test.
    
    Drop the TEST_OS hack, tests of current version recognizes RHEL 8.3 just
    fine (and in fact depends on it).
    
    Related: rhbz#1821193