Merge pull request #10546 from omoerbeek/rec-dns64-metrics

rec: Add dns64 metrics

diff --cc pdns/pdns_recursor.cc
Simple merge

diff --cc pdns/rec_channel_rec.cc
Simple merge

diff --cc pdns/recursordist/RECURSOR-MIB.txt
Simple merge

diff --cc pdns/recursordist/docs/settings.rst
Simple merge

diff --cc pdns/syncres.hh
Simple merge

diff --cc pdns/ws-recursor.cc
Simple merge