Add "dns-domain" parameter to Network class. Also check
backend extensions and send an error message in case of
an argument (like dns-domain) is sent and the extension is
missing (dns-integration in this case).
Change-Id: I7303658c27d9b9f2d8381ccea0b29e96909cab54
Closes-Bug: 1633214
Partial-Bug: 1547736