stepfunctions-tasks: emr-create-cluster - add support for managedScalingPolicy

### Describe the feature

When creating an EMR cluster in a step function it's possible to create a managed scaling policy when authoring amazon states language json. However, there's no way to do this in cdk that I can see. Would it be possible to add managed scaling policy support in cdk?

### Use Case

I want to create an EMR cluster with emr managed scaling in a step function with cdk.

### Proposed Solution

_No response_

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

2.55.1

### Environment details (OS name and version, etc.)

macos

Start at the stepfunctions-tasks EMR create-cluster construct and trace how its cluster properties are rendered into Amazon States Language. Check the corresponding construct tests and compare the generated definition with the managed scaling policy shape; done means CDK users can configure the policy and the synthesized state includes it.

Written by the indexing model from the issue text.