Add presets and variant
    
    The presets are needed for the system to function after installation.
    See https://bugzilla.redhat.com/show_bug.cgi?id=1506844
    
    The variant_id is necessary to set up the proper default firewall
    rules as well as display the Cockpit login information at the text
    login prompt.
    
    Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>