Fixes “stored properties cannot be marked @available” compiler error

Xcode 13 and earlier allowed us to mark lazy stored properties with @available, but it turns out this was never actually supported. Xcode 14 now throws a compiler error, so we work around it by converting lazy @available properties into computed properties, backed by typed-erased lazy ivars.

AltStore/AppDelegate.swift

@@ -34,11 +34,27 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     var window: UIWindow?
     
     @available(iOS 14, *)
-    private lazy var intentHandler = IntentHandler()
+    private var intentHandler: IntentHandler {
+        get { _intentHandler as! IntentHandler }
+        set { _intentHandler = newValue }
+    }
     
     @available(iOS 14, *)
-    private lazy var viewAppIntentHandler = ViewAppIntentHandler()
-
+    private var viewAppIntentHandler: ViewAppIntentHandler {
+        get { _viewAppIntentHandler as! ViewAppIntentHandler }
+        set { _viewAppIntentHandler = newValue }
+    }
+    
+    private lazy var _intentHandler: Any = {
+        guard #available(iOS 14, *) else { fatalError() }
+        return IntentHandler()
+    }()
+    
+    private lazy var _viewAppIntentHandler: Any = {
+        guard #available(iOS 14, *) else { fatalError() }
+        return ViewAppIntentHandler()
+    }()
+    
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool
     {
         // Register default settings before doing anything else.

AltStore/Managing Apps/AppManager.swift

@@ -46,9 +46,6 @@ class AppManager
 {
     static let shared = AppManager()
     
-    @available(iOS 13, *)
-    private(set) lazy var publisher: AppManagerPublisher = AppManagerPublisher()
-    
     private(set) var updatePatronsResult: Result<Void, Error>?
     
     private let operationQueue = OperationQueue()
@@ -67,8 +64,27 @@ class AppManager
         }
     }
     
-    @available(iOS 13.0, *)
-    private lazy var cancellables = Set<AnyCancellable>()
+    @available(iOS 13, *)
+    private(set) var publisher: AppManagerPublisher {
+        get { _publisher as! AppManagerPublisher }
+        set { _publisher = newValue }
+    }
+    
+    @available(iOS 13, *)
+    private(set) var cancellables: Set<AnyCancellable> {
+        get { _cancellables as! Set<AnyCancellable> }
+        set { _cancellables = newValue }
+    }
+    
+    private lazy var _publisher: Any = {
+        guard #available(iOS 13, *) else { fatalError() }
+        return AppManagerPublisher()
+    }()
+    
+    private lazy var _cancellables: Any = {
+        guard #available(iOS 13, *) else { fatalError() }
+        return Set<AnyCancellable>()
+    }()
     
     private init()
     {