(stepfunctions-tasks): relax inputDataConfig: Channel[] to any[]

### Describe the feature

We have a use case where a json payload with Sagemaker training job definitions are passed in to APIGateway -> StepFunction -> Sagemaker. The architecture can serve different types of models with varying number of inputs. The json payload is not explicitly available at package build time but only much later when trigger APIGateway.
With "inputDataConfig: Channel[]", s3DataSource is a required field of Channel object, it's impossible to assemble list of Channel objects since the json is not available and can't be accessed. Relaxing it to any[] would solve the problem as we can just pass around the whole list without the need to access into each item. Could you please help with this? Thanks

### Use Case

Our model hosting infrastructure should support all types of training models in our team with variable number of inputs.

### Proposed Solution

Change
inputDataConfig: Channel[]
to
inputDataConfig: any[]
https://github.com/aws/aws-cdk/blob/74318c7d22bfc00de9e005f68a0a6aaa58c7db39/packages/%40aws-cdk/aws-stepfunctions-tasks/lib/sagemaker/create-training-job.ts L123

### Other Information

_No response_

### Acknowledgements

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

### CDK version used

CDKv2, CDKBuild-4.x

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

Linux