MINOR: Add entity types in streams group RPCs

[lucasbru]

These can be used to implement transformations on top of the RPC
definitions. Group IDs were already marked. This PR additionally adds
the entityType for all topic names.

Reviewers: Matthias J. Sax [email protected]

[Copilot]

Pull Request Overview

Adds entityType metadata to various fields in the StreamsGroup RPC JSON schemas to support transformations on RPC definitions.

• Introduces entityType for error messages and topic names in heartbeat and describe RPC responses
• Fixes a comment typo in the StreamsGroupHeartbeatRequest header
• Adds entityType for topic fields in heartbeat request and describe response schemas

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
clients/src/main/resources/common/message/StreamsGroupHeartbeatResponse.json	Added entityType to ErrorMessage, StatusDetail, and Topic fields
clients/src/main/resources/common/message/StreamsGroupHeartbeatRequest.json	Corrected header comment and added entityType to SourceTopics, RepartitionSinkTopics, and TopicInfo Name
clients/src/main/resources/common/message/StreamsGroupDescribeResponse.json	Added entityType to ErrorMessage, SourceTopics, RepartitionSinkTopics, and TopicInfo Name

Comments suppressed due to low confidence (4)

clients/src/main/resources/common/message/StreamsGroupHeartbeatResponse.json:43

• Consider adding or updating unit tests to verify that the new entityType attribute for ErrorMessage is correctly parsed and applied in downstream transformations.

    { "name": "ErrorMessage", "type": "string", "versions": "0+", "nullableVersions": "0+", "default": "null", "entityType": "errorMessage",

clients/src/main/resources/common/message/StreamsGroupHeartbeatRequest.json:53

• Add tests to ensure that entityType: \"topicName\" on SourceTopics is correctly handled by any schema validation or code generation tools that consume these JSON files.

            { "name": "SourceTopics", "type": "[]string", "versions": "0+", "entityType": "topicName",

clients/src/main/resources/common/message/StreamsGroupDescribeResponse.json:39

• Introduce or update integration tests to confirm that downstream consumers receive and interpret the entityType metadata on ErrorMessage as expected.

        { "name": "ErrorMessage", "type": "string", "versions": "0+", "nullableVersions": "0+", "default": "null", "entityType": "errorMessage",

clients/src/main/resources/common/message/StreamsGroupHeartbeatRequest.json:23

• [nitpick] Consider adding a brief note in the file header or a shared spec document explaining the purpose and allowed values for the new entityType property so it's clear to future readers.

  // The StreamsGroupHeartbeatRequest API is added as part of KIP-1071 and is still under