Update objc2 version (#2936)

* Upgrade to objc2 v0.4.0 and icrate v0.0.3

* Fix `touchBar` method

* Use ClassType::alloc

* Use #[method_id(...)] functionality in declare_class!

src/platform_impl/macos/appkit/text_input_client.rs

@@ -0,0 +1,9 @@
+use objc2::{extern_protocol, ProtocolType};
+
+extern_protocol!(
+    pub(crate) unsafe trait NSTextInputClient {
+        // TODO: Methods
+    }
+
+    unsafe impl ProtocolType for dyn NSTextInputClient {}
+);