editor: Dismiss drag selection when dropped outside editor (#32382)

This PR fixes two issues:

1. On macOS, using Alt to copy the selection instead of cutting it.
2. Dropping the drag selection outside the editor dismisses it.  


https://github.com/user-attachments/assets/341e21c3-3eca-4e58-9bcc-8ec1de18e999


Release Notes:

- N/A

---------

Co-authored-by: Smit Barmase <heysmitbarmase@gmail.com>

crates/editor/src/editor.rs

@@ -918,6 +918,7 @@ enum SelectionDragState {
     Dragging {
         selection: Selection<Anchor>,
         drop_cursor: Selection<Anchor>,
+        hide_drop_cursor: bool,
     },
 }