detect_resolve1_resolv_conf() detects if systemd-resolved is enabled and
manages /etc/resolv.conf.
get_resolve1_nameservers() gets upstream DNS servers from
systemd-resolved's D-Bus interface.
get_dnspython_nameservers() gets upstream DNS servers from
/etc/resolv.conf via dns.python.
get_nameservers() gets a list of unique, non-loopback DNS server IP
addresses.
Also fixes setup.py to include D-Bus for ipalib instead of ipapython.
See: https://pagure.io/freeipa/issue/8275
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
