Async Assistant Streaming Helpers

[metaskills]

Confirm this is a feature request for the Node library and not the underlying OpenAI API.

• [X] This is a feature request for the Node library

Describe the feature or improvement you're requesting

When using the Assistant Streaming Helpers it is sometimes desirable to have an async/await level of control for the event listener. For example, an imageFileDone listener that would move a file to a new destination as part of tools being submitted.

Additional context

I am the author of Experts.js (https://github.com/metaskills/experts) and I felt this particular pain point in a few of my projects. I've not heard of other's needs for this behavior. That said, I thought that would be helpful for more context.

https://github.com/metaskills/experts?tab=readme-ov-file#streaming--events

Thanks y'all.