use DragEvent not MouseEvent for drag events (#3137)

* use DragEvent not MouseEvent for drag events

* Simplify drag events and remove WebDragData struct

* use DragEvent not MouseEvent for drag events

* re-add the web_sys event reference for drag + mouse data

* remove now vestigial impls for MouseEvent

---------

Co-authored-by: Matt Hunzinger <matthunz2@gmail.com>

packages/web/src/events/load.rs

@@ -23,7 +23,7 @@ impl HasImageData for WebImageEvent {
     }
 
     fn as_any(&self) -> &dyn Any {
-        &self.raw as &dyn Any
+        &self.raw
     }
 }