Verified that this works locally. I modeled it after how basedpyright
and pyright work. Here is a screenshot of what it looks like (issue has
screenshots of the old state):

<img width="593" height="258" alt="Screenshot 2025-11-07 at 2 40 50 PM"
src="https://github.com/user-attachments/assets/5d2371fc-360b-422f-ba59-0a95f2083c87"
/>

Closes #42232

Release Notes:

- python/ty: Code completion menu now shows packages that will be
imported when a given entry is accepted.