[Feature] startAfter / start_after in Durable Object list_with_options

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Description

The JS API for transactional storage in durable objects supports a field called "startAfter" on ListOptions: https://developers.cloudflare.com/durable-objects/api/transactional-storage-api/

This is not exposed through the Rust ListOptions type, and I can't figure out how to get access to the lower-level raw JS API that would allow me to pass my own list options object.