assistant: Insert creases for tool uses (#17330)

This PR makes it so we create creases for each of the tool uses in the
context editor.

<img width="1290" alt="Screenshot 2024-09-03 at 5 37 33 PM"
src="https://github.com/user-attachments/assets/94e943fd-3f05-4bc4-9672-94bff42ec500">

Release Notes:

- N/A