Make the Zed2 window movable (#3218)

This PR makes the Zed2 window movable and fixes a crash related to a
`todo!()` that wasn't necessary.

Release Notes:

- N/A

crates/workspace2/src/dock.rs

@@ -622,7 +622,7 @@ impl StatusItemView for PanelButtons {
         _active_pane_item: Option<&dyn crate::ItemHandle>,
         _cx: &mut ViewContext<Self>,
     ) {
-        todo!()
+        // todo!(This is empty in the old `workspace::dock`)
     }
 }