feat: support horizontal mouse scrolling in buffers

src/session.rs

@@ -274,6 +274,10 @@ impl EditorSession {
         self.editor.scroll_diff(focus, down);
     }
 
+    pub(crate) fn scroll_diff_horizontal(&mut self, focus: Focus, right: bool, width: usize) {
+        self.editor.scroll_diff_horizontal(focus, right, width);
+    }
+
     pub fn handle(&mut self, input: Input) {
         self.cancel_pending_popup_request();
         let invocation = self.editor.handle(input);