docdb: support for specifying storage type for Cluster

[badmintoncryer]

Describe the feature

Specify storage type for DocDB cluster from L2 construct.

Use Case

DocDB cluster supports for specifying storage type but CDK cannot configure it.

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

CDK version used

2.141.0

Environment details (OS name and version, etc.)

irrelevant