[[PR Description]]

This PR styles the hover popover, and sets it on the [second elevation
level](https://zed-docs.vercel.app/doc/ui2/trait.StyledExt.html#method.elevation_2).

![CleanShot 2023-11-29 at 14 55
55@2x](https://github.com/zed-industries/zed/assets/1714999/01589b2a-d6e2-4baa-ba5d-050f06cf2c58)


Release Notes:

- N/A