Add support for multiple certificates/formats to ipa-cacert-manage
    
    Only a single cert in DER or PEM format would be loaded from the
    provided file. Extend this to include PKCS#7 format and load all
    certificates found in the file.
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    
    https://pagure.io/freeipa/issue/7579
    
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>