aws-redshift-alpha: Add support for RG node types

### Describe the feature

Add support to deploy the [RG node types](https://docs.aws.amazon.com/redshift/latest/mgmt/working-with-clusters.html#rs-about-clusters-and-nodes)

### Use Case

I would like to use the RG node types in my deployments

### Proposed Solution

_No response_

### Other Information

_No response_

### Acknowledgements

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

### AWS CDK Library version (aws-cdk-lib)

2.259.0

### AWS CDK CLI version

2.1127.0 (build 425ccb0)

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

mac osx

Start at the aws-redshift-alpha implementation and compare its supported node types with the linked Amazon Redshift documentation. Done means RG node types can be selected in AWS CDK deployments.

Written by the indexing model from the issue text.