Support interactive prompt for ntp options
    
    As the FreeIPA server is no longer a NTP service
    providing instance its clients and replicas
    configuration of time service can not be handled
    as it was before change to chrony. Configuration
    using master FQDN or autodiscovery for DNS record
    would make no difference because every FreeIPA
    instance is only chrony client now and does not
    update DNS _ntp._udp record.
    
    FreeIPA now asks user for NTP source server
    or pool address in interactive mode if there is
    no server nor pool specified and autodiscovery
    has not found any NTP source in DNS records.
    
    Resolves: https://pagure.io/freeipa/issue/7747
    Reviewed-By: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>