Adding Key/Value Schema metadata attributes for KafkaEvent

[karthikpswamy]

As part of Schema Registry integration with Kafka Event Source Mapping (ESM), we are adding schema metadata attributes (schemaId and dataFormat) to the KafkaEvent object. These attributes will only be populated when Kafka ESM is integrated with Schema Registry. This enhancement maintains backward compatibility for existing users.

[maxday]

Thanks, this looks good to me!

If we want to release a new version now, could you create a follow-up PR to

1. minor-bump the version in pom (here: https://github.com/aws/aws-lambda-java-libs/blob/main/aws-lambda-java-events/pom.xml#L8)
2. update this file as well https://github.com/aws/aws-lambda-java-libs/blob/main/aws-lambda-java-events/RELEASE.CHANGELOG.md
3. bump the version where the event lib is referenced (here is an example from latest release: befa67d)