SSSCTL: user-checks does not show custom attributes
    
    "sssctl user-checks" also query the IFP interface of sssd. The problem
    is, that this command only displays POSIX user attrs, no matter if we
    configured the InfoPipe for additional user attributes.
    
    With this patch additional attributes are also printed out.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3866
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-by: Sumit Bose <sbose@redhat.com>