This PR adds a new feature, allowing to 'refuse' dynamically blocked queries instead of dropping them, and fixes two issues:
dnsdist: Dyn blocks can now refuse queries instead of dropping them
dnsdist: Add regression tests for dynamic blocks
dnsdist: Store the TCP response header in the response ring
Until now we stored the query header in the response ring for TCP
dnsdist: Don't mix "real" and monotonic time for TCP queries
Otherwise the time stored in the response ring makes no sense.