WIP!

In light of having more control over blame popover from editor.

This fixes: https://github.com/zed-industries/zed/issues/28645,
https://github.com/zed-industries/zed/issues/26304

- [x] Initial rendering
- [x] Handle smart positioning (edge detection, etc)
- [x] Delayed hovering, release, etc
- [x] Test blame message selection
- [x] Fix tagged issues

Release Notes:

- Git inline blame popover now dismisses when the cursor is moved, the
editor is scrolled, or the command palette is opened.