validate: add kr_rrset_validation_ctx_t::log_qry

validate: add kr_rrset_validation_ctx_t::log_qry

... so we can use it for more precise logging.  Some calls get simpler.
In particular, without the associated request, we can't produce anything
into trace-logs, which could be confusing.  Normal logs will benefit, too.
(more precise replacement of WITH_VERBOSE will come in a subsequent commit)