Description

cimpl.Message has many set methods like set_value, set_key, set_headers, etc.
It would be useful to have a set_error as well.

The use case if that the message is received by some wrapper that will parse the payload (xml or json) and validate against a schema, and if that fails, the wrapper code can set the error and then pass the message object further downstream.

Checklist

Please provide the following information:

• confluent-kafka-python and librdkafka version (confluent_kafka.version() and confluent_kafka.libversion()):
• Apache Kafka broker version:
• Client configuration: {...}
• Operating system:
• Provide client logs (with 'debug': '..' as necessary)
• Provide broker log excerpts
• Critical issue