[FLINK-31049] [flink-connector-kafka]Add support for Kafka record headers to KafkaSink

[AlexAxeman]

What is the purpose of the change

The default org.apache.flink.connector.kafka.sink.KafkaSink does not support adding Kafka record headers when using KafkaRecordSerializationSchemaBuilder, which is the most convenient way to create a Kafka sink. This PR adds support for Kafka headers to KafkaRecordSerializationSchemaBuilder.

Brief change log

• Implemented a HeaderProducer that allows creating Headers from the input element
• Added setters to KafkaRecordSerializationSchemaBuilder to allow setting a HeaderProducer
• Added an optional HeaderProducer constructor argument to KafkaRecordSerializationSchemaWrapper that now uses a ProducerRecord constructor that includes the headers.

Verifying this change

Please make sure both new and modified tests in this PR follows the conventions defined in our code quality guide: https://flink.apache.org/contributing/code-style-and-quality-common.html#testing

This change added tests and can be verified as follows:

• Added tests to KafkaRecordSerializationSchemaBuilderTest

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): yes
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? yes?
• If yes, how is the feature documented? JavaDocs

[flinkbot]

CI report:

• 1df0da7 Azure: SUCCESS

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[MartijnVisser]

@AlexAxeman Given that https://issues.apache.org/jira/browse/FLINK-30859 will be worked on shortly, could you open this PR towards apache/flink-connector-kafka:main

[tzulitai]

Thanks for opening the PR @AlexAxeman! After you reopen the PR against apache/flink-connector-kafka:main, please feel free to ping me for a review on the change.

[davidradl]

@tzulitai @MartijnVisser I see #22797 , this pr is no longer relevant to this repository, I suggest closing this pr and porting the change to the new Flink connector kafka repo if it is still relevant.

[AlexAxeman]

It was implemented in the new repo in this PR.