Allow SplitAndMove on panes (#38034)

Updates #19350

Release Notes:

- Add `pane::SplitAndMove{Up,Down,Left,Right}` to allow creating a split
without cloning the current buffer.

crates/workspace/src/workspace.rs

@@ -3929,8 +3929,15 @@ impl Workspace {
                     item: item.boxed_clone(),
                 });
             }
-            pane::Event::Split(direction) => {
-                self.split_and_clone(pane.clone(), *direction, window, cx);
+            pane::Event::Split {
+                direction,
+                clone_active_item,
+            } => {
+                if *clone_active_item {
+                    self.split_and_clone(pane.clone(), *direction, window, cx);
+                } else {
+                    self.split_and_move(pane.clone(), *direction, window, cx);
+                }
             }
             pane::Event::JoinIntoNext => {
                 self.join_pane_into_next(pane.clone(), window, cx);
@@ -4044,6 +4051,24 @@ impl Workspace {
         new_pane
     }
 
+    pub fn split_and_move(
+        &mut self,
+        pane: Entity<Pane>,
+        direction: SplitDirection,
+        window: &mut Window,
+        cx: &mut Context<Self>,
+    ) {
+        let Some(item) = pane.update(cx, |pane, cx| pane.take_active_item(window, cx)) else {
+            return;
+        };
+        let new_pane = self.add_pane(window, cx);
+        new_pane.update(cx, |pane, cx| {
+            pane.add_item(item, true, true, None, window, cx)
+        });
+        self.center.split(&pane, &new_pane, direction).unwrap();
+        cx.notify();
+    }
+
     pub fn split_and_clone(
         &mut self,
         pane: Entity<Pane>,