Move iOS and macOS implementations into new apple module (#3756)

Move iOS and macOS implementations to a shared folder called `apple`, to allow
us to reduce the code-duplication between these platforms in the future.

The folder structure is now:
- `src/platform_impl/apple/`
  - `appkit/`
  - `uikit/`
  - `example_shared_file.rs`
  - `mod.rs`

* Add preliminary support for tvOS, watchOS and visionOS
* Reduce duplication in Cargo.toml when specifying dependencies

src/platform_impl/macos/window.rs

@@ -1,126 +0,0 @@
-#![allow(clippy::unnecessary_cast)]
-
-use objc2::rc::{autoreleasepool, Retained};
-use objc2::{declare_class, mutability, ClassType, DeclaredClass};
-use objc2_app_kit::{NSResponder, NSWindow};
-use objc2_foundation::{MainThreadBound, MainThreadMarker, NSObject};
-
-use super::event_loop::ActiveEventLoop;
-use super::window_delegate::WindowDelegate;
-use crate::error::OsError as RootOsError;
-use crate::window::WindowAttributes;
-
-pub(crate) struct Window {
-    window: MainThreadBound<Retained<WinitWindow>>,
-    /// The window only keeps a weak reference to this, so we must keep it around here.
-    delegate: MainThreadBound<Retained<WindowDelegate>>,
-}
-
-impl Drop for Window {
-    fn drop(&mut self) {
-        self.window.get_on_main(|window| autoreleasepool(|_| window.close()))
-    }
-}
-
-impl Window {
-    pub(crate) fn new(
-        window_target: &ActiveEventLoop,
-        attributes: WindowAttributes,
-    ) -> Result<Self, RootOsError> {
-        let mtm = window_target.mtm;
-        let delegate = autoreleasepool(|_| {
-            WindowDelegate::new(window_target.app_delegate(), attributes, mtm)
-        })?;
-        Ok(Window {
-            window: MainThreadBound::new(delegate.window().retain(), mtm),
-            delegate: MainThreadBound::new(delegate, mtm),
-        })
-    }
-
-    pub(crate) fn maybe_queue_on_main(&self, f: impl FnOnce(&WindowDelegate) + Send + 'static) {
-        // For now, don't actually do queuing, since it may be less predictable
-        self.maybe_wait_on_main(f)
-    }
-
-    pub(crate) fn maybe_wait_on_main<R: Send>(
-        &self,
-        f: impl FnOnce(&WindowDelegate) -> R + Send,
-    ) -> R {
-        self.delegate.get_on_main(|delegate| f(delegate))
-    }
-
-    #[cfg(feature = "rwh_06")]
-    #[inline]
-    pub(crate) fn raw_window_handle_rwh_06(
-        &self,
-    ) -> Result<rwh_06::RawWindowHandle, rwh_06::HandleError> {
-        if let Some(mtm) = MainThreadMarker::new() {
-            Ok(self.delegate.get(mtm).raw_window_handle_rwh_06())
-        } else {
-            Err(rwh_06::HandleError::Unavailable)
-        }
-    }
-
-    #[cfg(feature = "rwh_06")]
-    #[inline]
-    pub(crate) fn raw_display_handle_rwh_06(
-        &self,
-    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
-        Ok(rwh_06::RawDisplayHandle::AppKit(rwh_06::AppKitDisplayHandle::new()))
-    }
-}
-
-#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct WindowId(pub usize);
-
-impl WindowId {
-    pub const unsafe fn dummy() -> Self {
-        Self(0)
-    }
-}
-
-impl From<WindowId> for u64 {
-    fn from(window_id: WindowId) -> Self {
-        window_id.0 as u64
-    }
-}
-
-impl From<u64> for WindowId {
-    fn from(raw_id: u64) -> Self {
-        Self(raw_id as usize)
-    }
-}
-
-declare_class!(
-    #[derive(Debug)]
-    pub struct WinitWindow;
-
-    unsafe impl ClassType for WinitWindow {
-        #[inherits(NSResponder, NSObject)]
-        type Super = NSWindow;
-        type Mutability = mutability::MainThreadOnly;
-        const NAME: &'static str = "WinitWindow";
-    }
-
-    impl DeclaredClass for WinitWindow {}
-
-    unsafe impl WinitWindow {
-        #[method(canBecomeMainWindow)]
-        fn can_become_main_window(&self) -> bool {
-            trace_scope!("canBecomeMainWindow");
-            true
-        }
-
-        #[method(canBecomeKeyWindow)]
-        fn can_become_key_window(&self) -> bool {
-            trace_scope!("canBecomeKeyWindow");
-            true
-        }
-    }
-);
-
-impl WinitWindow {
-    pub(super) fn id(&self) -> WindowId {
-        WindowId(self as *const Self as usize)
-    }
-}