[ios] Remove AR module (#8442)

# Why

Completes two more checks from #8371.

# How

- Removed the `ARKit` directory from `Optional` directory from inside Exponent project.
- Removed the `AR` module export from `expo` in favor of a simple throwing export in `removed.ts`.
- Removed AR modules from versioned SDKs.

# Test Plan

`expo` package built. Expo client for iOS built too.

CHANGELOG.md

@@ -15,6 +15,7 @@ Package-specific changes not released in any SDK will be added here just before
 ### 🛠 Breaking changes
 
 - `react-native-view-shot` is no longer installed by default, install it with `expo install react-native-view-shot`. ([#7950](https://github.com/expo/expo/pull/7950) by [@evanbacon](https://github.com/evanbacon))
+- The AR module has been removed from the `expo` package. See https://expo.fyi/deprecating-ar for more information. ([#8442](https://github.com/expo/expo/pull/8442) by [@sjchmiela](https://github.com/sjchmiela))
 - **`expo-battery`**
   - Removed deprecated `isSupported` method. ([#7206](https://github.com/expo/expo/pull/7206) by [@bbarthec](https://github.com/bbarthec))
 - **`expo-camera`**

ExpoKit.podspec

@@ -43,11 +43,6 @@ Pod::Spec.new do |s|
     ss.source_files = 'ios/Exponent/Versioned/Optional/Payments/*.{h,m}'
   end
 
-  s.subspec "AR" do |ss|
-    ss.dependency "ExpoKit/Core"
-    ss.source_files = 'ios/Exponent/Versioned/Optional/ARKit/**'
-  end
-
   s.subspec "FaceDetector" do |ss|
     ss.dependency "EXFaceDetector"
   end