chg: usr: emit more helpful log for exceeding max-records-per-type

The new log message is emitted when adding or updating an RRset fails due to exceeding the max-records-per-type limit. The log includes the owner name and type, corresponding zone name, and the limit value. It will be emitted on loading a zone file, inbound zone transfer (both AXFR and IXFR), handling a DDNS update, or updating a cache DB. It's especially helpful in the case of zone transfer, since the secondary side doesn't have direct access to the offending zone data.

It could also be used for max-types-per-name, but this change doesn't implement it yet as it's much less likely to happen in practice.