Allow hovering over tooltips in git blame sidebar (#10466)

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

---------

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

crates/gpui/src/app.rs

@@ -1416,8 +1416,8 @@ pub struct AnyTooltip {
     /// The view used to display the tooltip
     pub view: AnyView,
 
-    /// The offset from the cursor to use, relative to the parent view
-    pub cursor_offset: Point<Pixels>,
+    /// The absolute position of the mouse when the tooltip was deployed.
+    pub mouse_position: Point<Pixels>,
 }
 
 /// A keystroke event, and potentially the associated action