[Enhancement] Support delete consumer offset by consumer group and topic

### Before Creating the Enhancement Request

- [x] I have confirmed that this should be classified as an enhancement rather than a bug/feature.

### Summary

Support delete consumer offset by consumer group and topic.

### Motivation

When a consumer group subscribes to an unintended topic by mistake, the client will continuously report and update the consumer offset to the broker, causing the broker to persist the offset for this erroneous subscription. Since deleting the topic or the consumer group entirely is not desirable. other subscriptions under the same group or other groups consuming the same topic should not be affected. users need the ability to precisely clean up the consumer offset for a specific topic under a specific consumer group, without removing the topic or the group itself.

### Describe the Solution You'd Like

1. add a new request code.
2. provide a new sub command to delete consumer offset.

### Describe Alternatives You've Considered

No

### Additional Context

_No response_

The issue names no files or tests. Start by tracing the existing consumer-offset request handling and command-line subcommands, then determine how a request can target both a consumer group and topic. Done means a request code and subcommand can delete only that offset without removing the topic, consumer group, or unrelated subscriptions.

Written by the indexing model from the issue text.