Fix window double borrows (#23739)

Fix bugs caused by the window context PR, where the window could be on
the stack and is then requested from the App.
This PR also adds derive macros for `AppContext` and `VisualContext` so
that it's easy to define further contexts in API code, such as
`editor::BlockContext`.

Release Notes:

- N/A

crates/editor/src/element.rs

@@ -4147,9 +4147,9 @@ impl EditorElement {
             // In singleton buffers, we select corresponding lines on the line number click, so use | -like cursor.
             // In multi buffers, we open file at the line number clicked, so use a pointing hand cursor.
             if is_singleton {
-                window.set_cursor_style(CursorStyle::IBeam, hitbox);
+                window.set_cursor_style(CursorStyle::IBeam, &hitbox);
             } else {
-                window.set_cursor_style(CursorStyle::PointingHand, hitbox);
+                window.set_cursor_style(CursorStyle::PointingHand, &hitbox);
             }
         }
     }