[FEATURE] Add a spark compact commit protocol to merge small files

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/kyuubi/issues?q=is%3Aissue) and found no similar issues.

### Describe the feature

Add a spark compact commit protocol to merge small files

### Motivation

_No response_

### Describe the solution

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

- [X] Yes. I would be willing to submit a PR with guidance from the Kyuubi community to improve.
- [ ] No. I cannot submit a PR at this time.

Search the repository for existing Spark commit-protocol handling and related tests; the issue names no files or entry points. Clarify the intended small-file merge behavior and integration boundaries with the Kyuubi community, then define completion through targeted tests for the new protocol.

Written by the indexing model from the issue text.