Detection of PKI subsystem
    
    In order to know if ca/kra is installed locally, the code
    is calling pki-server subsystem-show _subsystem_
    and ensures that "Enabled: True" is in the output.
    
    If a subsystem fails to start, the command returns
    "Enabled: False" but it doesn't mean that the subsystem
    is not installed, it just means that it is not active
    right now.
    Same output if the subsystem has been disabled with
    pki-server subsystem-disable _subsystem_.
    
    The correct way to check if a subsystem is installed is to
    ensure that subsystem-show does not exit on error and
    contains "Enabled: ", whatever the value.
    
    Related: https://pagure.io/freeipa/issue/9330
    
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>