Remove EventLoopExtIOS::idiom and ios::Idiom (#2924)

Introduced in 3a7350c with unclear motivation.

Nowadays, this feature is incomplete and unsound, and the equivalent
functionality can be trivially achieved outside of `winit` using
`objc2-ui-kit`.

src/platform/ios.rs

@@ -66,22 +66,9 @@
 
 use std::os::raw::c_void;
 
-use crate::event_loop::EventLoop;
 use crate::monitor::{MonitorHandle, VideoModeHandle};
 use crate::window::{Window, WindowAttributes};
 
-/// Additional methods on [`EventLoop`] that are specific to iOS.
-pub trait EventLoopExtIOS {
-    /// Returns the [`Idiom`] (phone/tablet/tv/etc) for the current device.
-    fn idiom(&self) -> Idiom;
-}
-
-impl EventLoopExtIOS for EventLoop {
-    fn idiom(&self) -> Idiom {
-        self.event_loop.idiom()
-    }
-}
-
 /// Additional methods on [`Window`] that are specific to iOS.
 pub trait WindowExtIOS {
     /// Sets the [`contentScaleFactor`] of the underlying [`UIWindow`] to `scale_factor`.
@@ -379,24 +366,6 @@ pub enum ValidOrientations {
     Portrait,
 }
 
-/// The device [idiom].
-///
-/// [idiom]: https://developer.apple.com/documentation/uikit/uidevice/1620037-userinterfaceidiom?language=objc
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub enum Idiom {
-    Unspecified,
-
-    /// iPhone and iPod touch.
-    Phone,
-
-    /// iPad.
-    Pad,
-
-    /// tvOS and Apple TV.
-    TV,
-    CarPlay,
-}
-
 bitflags::bitflags! {
     /// The [edges] of a screen.
     ///