server-del: perform full master removal in managed topology
    
    This patch implements most of the del_master_managed() functionality as a part
    of `server-del` command.
    
    `server-del` nows performs these actions:
      * check topology connectivity
      * check that at least one CA/DNS server and DNSSec masters are left
        after removal
      * cleanup all LDAP entries/attributes exposing information about the master
      * cleanup master DNS records
      * remove master and service principals
      * remove master entry from LDAP
      * check that all segments pointing to the master were removed
    
      `server-del` now accepts the following options:
      * `--force`: force master removal even if it doesn't exist
      * `--ignore-topology-disconnect`: ignore errors arising from disconnected
        topology before and after master removal
      * `--ignore-last-of-role`: remove master even if it is last DNS server,
        and DNSSec key master. The last CA will *not* be removed regardless of
        this option.
    
    https://fedorahosted.org/freeipa/ticket/5588
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>