Kafka External Stream to support read the Avro-encoded message key #915
Description
Use case
Today the message key is read as a string. If the producer create the message with Avro encoded message key, cannot read the content. This is also brought up in ClickHouse/ClickHouse#57664
Describe the solution you'd like
Add new settings in the kafka externals stream to set the schema name for the message key, then decode the message key as a JSON string (otherwise the type will be too complex)
Describe alternatives you've considered
Additional context