[FEATURE] Support listing all engines

### 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

The `ListEngines` function doesn't support listing all active engines. We should support it so that an administrator can manage the cluster resources.

This could be a new RESTful admin GET API.

### Motivation

_No response_

### Describe the solution

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

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

Start by tracing the existing ListEngines function and reviewing any current RESTful admin API entry points. Define how the API should list all active engines so administrators can manage cluster resources, then verify that the complete active-engine list is returned.

Written by the indexing model from the issue text.