Refactor macOS to use new objc2 features (#2465)

* Remove UnownedWindow::inner_rect

* Refactor custom view to use much less `unsafe`

The compiler fence is safe to get rid of now since `interpretKeyEvents` takes `&mut self`

* Refactor Window to use much less unsafe

* Refactor NSApplication usage to have much less unsafe

* Remove cocoa dependency

* Enable `deny(unsafe_op_in_unsafe_fn)` on macOS

Also re-enable clippy `let_unit_value` lint

* Remove #[macro_use] on macOS

* Refactor window delegate to use much less unsafe

src/platform_impl/macos/appkit/mod.rs

@@ -1,18 +1,59 @@
-#![deny(unsafe_op_in_unsafe_fn)]
+//! Safe bindings for the AppKit framework.
+//!
+//! These are split out from the rest of `winit` to make safety easier to review.
+//! In the future, these should probably live in another crate like `cacao`.
+//!
+//! TODO: Main thread safety.
 // Objective-C methods have different conventions, and it's much easier to
 // understand if we just use the same names
 #![allow(non_snake_case)]
+#![allow(clippy::too_many_arguments)]
+#![allow(clippy::enum_variant_names)]
+#![allow(non_upper_case_globals)]
 
 mod application;
+mod button;
+mod color;
+mod control;
 mod cursor;
+mod event;
 mod image;
+mod menu;
+mod menu_item;
+mod pasteboard;
 mod responder;
+mod screen;
+mod text_input_context;
+mod version;
 mod view;
 mod window;
 
-pub(crate) use self::application::NSApplication;
+pub(crate) use self::application::{
+    NSApp, NSApplication, NSApplicationActivationPolicy, NSApplicationPresentationOptions,
+    NSRequestUserAttentionType,
+};
+pub(crate) use self::button::NSButton;
+pub(crate) use self::color::NSColor;
+pub(crate) use self::control::NSControl;
 pub(crate) use self::cursor::NSCursor;
+#[allow(unused_imports)]
+pub(crate) use self::event::{
+    NSEvent, NSEventModifierFlags, NSEventPhase, NSEventSubtype, NSEventType,
+};
 pub(crate) use self::image::NSImage;
+pub(crate) use self::menu::NSMenu;
+pub(crate) use self::menu_item::NSMenuItem;
+pub(crate) use self::pasteboard::{NSFilenamesPboardType, NSPasteboard, NSPasteboardType};
 pub(crate) use self::responder::NSResponder;
-pub(crate) use self::view::NSView;
-pub(crate) use self::window::NSWindow;
+#[allow(unused_imports)]
+pub(crate) use self::screen::{NSDeviceDescriptionKey, NSScreen};
+pub(crate) use self::text_input_context::NSTextInputContext;
+pub(crate) use self::version::NSAppKitVersion;
+pub(crate) use self::view::{NSTrackingRectTag, NSView};
+pub(crate) use self::window::{
+    NSBackingStoreType, NSWindow, NSWindowButton, NSWindowLevel, NSWindowOcclusionState,
+    NSWindowStyleMask, NSWindowTitleVisibility,
+};
+
+#[link(name = "AppKit", kind = "framework")]
+extern "C" {}