Add "new window" option to the dock menu (#12067)

Fixes: #11651
Co-Authored-By: versecafe <147033096+versecafe@users.noreply.github.com>



Release Notes:

- Added a "New Window" item to the dock menu
([#11651](https://github.com/zed-industries/zed/issues/11651)).

---------

Co-authored-by: versecafe <147033096+versecafe@users.noreply.github.com>

crates/gpui/src/platform/windows/platform.rs

@@ -450,6 +450,7 @@ impl Platform for WindowsPlatform {
 
     // todo(windows)
     fn set_menus(&self, menus: Vec<Menu>, keymap: &Keymap) {}
+    fn set_dock_menu(&self, menus: Vec<MenuItem>, keymap: &Keymap) {}
 
     fn on_app_menu_action(&self, callback: Box<dyn FnMut(&dyn Action)>) {
         self.state.borrow_mut().callbacks.app_menu_action = Some(callback);