kernel: add test for CephFS labeling
    
    The test verifies expected behavior of CephFS security label support
    across distros.
    
    Note that for the test to work RHEL, an appropriate Ceph repo must be
    installed. A scriptlet that sets this up can be provided via the
    INSTALL_SCRIPTLET parameter.
    
    Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>