cert: include certificate chain in cert command output
    
    Include the full certificate chain in the output of cert-request, cert-show
    and cert-find if --chain or --all is specified.
    
    If output file is specified in the CLI together with --chain, the full
    certificate chain is written to the file.
    
    https://pagure.io/freeipa/issue/6547
    
    Reviewed-By: David Kupka <dkupka@redhat.com>