assistant2: Render messages as Markdown (#21496)

This PR updates Assistant 2 to render the messages in the thread as
Markdown:

<img width="1138" alt="Screenshot 2024-12-03 at 6 09 27 PM"
src="https://github.com/user-attachments/assets/c1c44fde-1efb-43cf-b9c9-768e6974c753">

Release Notes:

- N/A

Marshall Bowers committed 1y ago

9f459ba573b8c029c89dbbc7a8edca6d1f7b712e

Parent: ecaf445

Committed by GitHub <noreply@github.com> on 12/3/2024, 11:32:13 PM