Process Messages in DQL (Dead Letter Queue)

[hekike]

When Kafka Connect ClickHouse gets a malformed message, it sends the entire batch to DQL.
It means the DQL topic can have bad and good messages mixed. Ideally, OpenMeter would have a secondary consumer for DQL, which runs validation against those messages and tries to re-process the ones that it finds the corresponding meter and matches the validator.

Related to: #225