I couldn't make my Windows 10 or 11 query a non-standard port. It kept
complaining about "The parameter is incorrect.", so as a result the unit
test doesn't actually test the new feature there. I can't find a single
example of this on the Internet; my speculation is that the backend API
that DnsQueryEx uses does not support setting port numbers
(DnsQuery_{A,W} didn't offer that option).
[ChangeLog][QtNetwork][QDnsLookup] Added setNameserverPort().
Change-Id: I3e3bfef633af4130a03afffd175d60a581cc0a9c
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>