Revert window::close producing a window::Id

Instead, subscribing to `window::close_events` is
preferable; since most use cases will want to react
to the user closing a window as well.

winit/src/program.rs

@@ -1211,10 +1211,9 @@ fn run_action<P, C>(
 
                 *is_window_opening = true;
             }
-            window::Action::Close(id, channel) => {
+            window::Action::Close(id) => {
                 let _ = window_manager.remove(id);
                 let _ = ui_caches.remove(&id);
-                let _ = channel.send(id);
 
                 events.push((
                     id,