This design polish PR brings the project panel context menu into better
alignment with other editors, better follows system patterns and
identifies focus shifting actions with the `…` indicator (like adding a
new folder to a project, which will open a modal window.)

## Before & After:

**Root level**

![CleanShot - 2024-04-11 at 22 40
53@2x](https://github.com/zed-industries/zed/assets/1714999/aa103d14-0747-4be9-acbf-1c3ed0542a15)

**Folder level**

![CleanShot - 2024-04-11 at 22 43
45@2x](https://github.com/zed-industries/zed/assets/1714999/180224f2-26d1-45bd-8f78-822f46068a6d)

**File level**

![CleanShot - 2024-04-11 at 22 44
56@2x](https://github.com/zed-industries/zed/assets/1714999/67edd0ae-bcb6-4920-a480-c4d50c6bccfa)

Note: That double divider in the after has been fixed 😅

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Release Notes:

- Improved ordering and organization of context menus in the project
panel to bring them closer to those in similar applications.