[DevTools] Include the description derived from the promise (#34017)

Stacked on #34016.

This is using the same thing we already do for the performance track to
provide a description of the I/O based on the content of the resolved
Promise. E.g. a Response's URL.

<img width="375" height="388" alt="Screenshot 2025-07-28 at 1 09 49 AM"
src="https://github.com/user-attachments/assets/f3fdc40f-4e21-4e83-b49e-21c7ec975137"
/>