Create a producerName field for DeadLetterPolicy

[crossoverJie]

Fixes #21441

Motivation

Add producerName for dead letter producer, easier to locate problems.

Modifications

public class DeadLetterPolicy {

    /**
     * Name of the dead letter producer name.
     */
	private String producerName;
}

Add a new field producerName in DeadLetterPolicy class.

Verifying this change

• Make sure that the change passes the CI checks.

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

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: crossoverJie#15

[RobertIndie]

This is a change for the public API. We need a PIP to get approved to add this field.

[crossoverJie]

Close by #21589