determine_rhel_state: recognize "Launch" phase
    
    There is now a period in the schedule where submissions are no longer
    accepted as Exceptions before the actual release of the minor release.
    This patch adds support for identifying that phase and handling it
    cleanly.
    
    Fixes: CS-2620
    
    Signed-off-by: Stephen Gallagher <sgallagh@redhat.com>