Add tests for CVE-2022-2795

Add tests for CVE-2022-2795

Add a test ensuring that the amount of work fctx_getaddresses() performs
for any encountered delegation is limited: delegate example.net to a set
of 1,000 name servers in the redirect.com zone, the names of which all
resolve to IP addresses that nothing listens on, and query for a name in
the example.net domain, checking the number of times the findname()
function gets executed in the process; fail if that count is excessively
large.

Since the size of the referral response sent by ans3 is about 20 kB, it
cannot be sent back over UDP (EMSGSIZE) on some operating systems in
their default configuration (e.g. FreeBSD - see the
net.inet.udp.maxdgram sysctl).  To enable reliable reproduction of
CVE-2022-2795 (retry patterns vary across BIND 9 versions) and avoid
false positives at the same time (thread scheduling - and therefore the
number of fetch context restarts - vary across operating systems and
across test runs), extend bin/tests/system/resolver/ans3/ans.pl so that
it also listens on TCP and make "ns1" in the "resolver" system test
always use TCP when communicating with "ans3".

Also add a test (foo.bar.sub.tld1/TXT) that ensures the new limitations
imposed on the resolution process by the mitigation for CVE-2022-2795 do
not prevent valid, glueless delegation chains from working properly.

(cherry picked from commit 604d8f0b967563b0ba9dcd4f09559fdd9e21dfbe)