Improve UX of test prompt component in general

[adamdbrw]

This is a task that involves rethinking how the user can input prompt, reset model and get responses, and how they see model working (in progress), its response (e.g. just a summary sentence at first, but drop down to expand if needed). Also, how to visualise the model working automatically (that is, response is for human view but for automated consumption), and how to interrupt.

[jhanca-robotecai]

The chat window is now available. Some features such as message delivered will be added.