If you wanted to interrupt the current LLM response that's generating to
send a follow up message, you'd need to stop it first, type your new
message, and then send it. Now, you can just type your new message while
there's a response generating and send it. This will interrupt the
previous response generation and kick off a new one.

Release Notes:

- agent: Allow to send a new message while a response is generating,
interrupting the LLM to focus instead on the most recent prompt.