Update objc2 to v0.2.2 (#3702)

- Use new `bitflags!` support.
- Use `objc2-ui-kit`.
- Change usage of `Id` to `Retained`.

src/platform_impl/macos/window.rs

@@ -1,6 +1,6 @@
 #![allow(clippy::unnecessary_cast)]
 
-use objc2::rc::{autoreleasepool, Id};
+use objc2::rc::{autoreleasepool, Retained};
 use objc2::{declare_class, mutability, ClassType, DeclaredClass};
 use objc2_app_kit::{NSResponder, NSWindow};
 use objc2_foundation::{MainThreadBound, MainThreadMarker, NSObject};
@@ -11,9 +11,9 @@ use crate::error::OsError as RootOsError;
 use crate::window::WindowAttributes;
 
 pub(crate) struct Window {
-    window: MainThreadBound<Id<WinitWindow>>,
+    window: MainThreadBound<Retained<WinitWindow>>,
     /// The window only keeps a weak reference to this, so we must keep it around here.
-    delegate: MainThreadBound<Id<WindowDelegate>>,
+    delegate: MainThreadBound<Retained<WindowDelegate>>,
 }
 
 impl Drop for Window {