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/macos.rs

@@ -1,3 +1,4 @@
+use objc2::rc::Id;
 use std::os::raw::c_void;
 
 use crate::{
@@ -240,7 +241,7 @@ impl MonitorHandleExtMacOS for MonitorHandle {
     }
 
     fn ns_screen(&self) -> Option<*mut c_void> {
-        self.inner.ns_screen().map(|s| s as *mut c_void)
+        self.inner.ns_screen().map(|s| Id::as_ptr(&s) as _)
     }
 }