Dynamic session

[hemanth]

It would be useful to have getter and setter functions for systemPrompt and initialPrompts.

Use case: I have a session and need to know what the systemPrompt or initialPrompts passed to the create function was, so that I can display, verify, or update it. Any updates to either of these options should be reflected in the session.

[domenic]

We cannot have setters since the purpose of a session is to be immutable.

For getters, this is a subset of #51.

So, I will close this issue.