sudo: use "higher value wins" when ordering rules
    
    This commit changes the default ordering logic (lower value wins) to
    a correct one that is used by native ldap support. It also adds a new
    option sudo_inverse_order to switch to the original SSSD (incorrect)
    behaviour if needed.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/2682
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    (cherry picked from commit 52e3ee5c5ff2c5a4341041826a803ad42d2b2de7)