This introduces a new API on `StatefulInteractiveElement` to create a
tooltip that can be hovered, scrolled inside, and clicked:
`.hoverable_tooltip`.

Right now we only use it in the `git blame` gutter, but the plan is to
use the new hover/click/scroll behavior in #10398 to introduce new
git-blame-tooltips.

Release Notes:

- N/A

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Co-authored-by: Antonio <antonio@zed.dev>