ipatests: test_sudo: Add coverage for category ALL validation
    
    Makes sure sudorules behave correctly both when adding new entries
    with corresponding category set to ALL, and when setting the
    category to all when corresponding entries exist.
    
    The only exception of deny commands with cmdcategory ALL is
    covered as well.
    
    Reviewed-By: Petr Viktorin <pviktori@redhat.com>