(aws-stepfunctions-tasks): Add support for DynamoDBStream getShardIterator and getRecords actions

### Describe the feature

Step Functions support `arn:aws:states:::aws-sdk:dynamodbstreams:getShardIterator` and `arn:aws:states:::aws-sdk:dynamodbstreams:getRecords` resource types now. Please add CDK support for it.

### Use Case

I would like to be able to use L2 CDK constructs for all tasks, and GetShardIterator and GetRecords APIs for DynamoDB streams are currently missing

### Proposed Solution

Create new `DynamoDBStreamGetShardIterator` and `DynamoDBStreamGetRecords` classes that will implement `arn:aws:states:::aws-sdk:dynamodbstreams:getShardIterator` and `arn:aws:states:::aws-sdk:dynamodbstreams:getRecords` resources respectively.

Currently, the workaround is to use CustomState

### Other Information

_No response_

### Acknowledgements

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

### CDK version used

2.59.0

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

N/A

Start in the aws-stepfunctions-tasks implementations and compare existing AWS SDK task classes for analogous actions. Done means adding DynamoDBStreamGetShardIterator and DynamoDBStreamGetRecords L2 constructs that use the two specified DynamoDB Streams resource types, removing the need for CustomState.

Written by the indexing model from the issue text.