hickory-proto: NSEC3 closest-encloser proof validation enters unbounded loop on cross-zone responses

The NSEC3 closest-encloser proof validation in hickory-proto's 0.25.0-alpha.3 ... 0.25.2 and hickory-net's 0.26.0-alpha.1 .. 0.26.0 DnssecDnsHandle walks from the QNAME up to the SOA owner name, building a list of candidate encloser names. The iterator used assumes the QNAME is a descendant of th...