Dispatch cancel callback when the Lock view is interactively dismissed

Call onCancel when the Lock view controller modal is dismissed by the user
(by tapping outside its bounds on iPad).

This is not called when it's dismissed programmatically:
https://developer.apple.com/documentation/uikit/uiadaptivepresentationcontrollerdelegate/3229889-presentationcontrollerdiddismiss

Lock/LockViewController.swift

@@ -51,6 +51,7 @@ public class LockViewController: UIViewController {
         if #available(iOS 13.0, *) {
             self.isModalInPresentation = !lock.options.closable
         }
+        self.presentationController?.delegate = self
         self.router = lock.classicMode ? ClassicRouter(lock: lock, controller: self) : PasswordlessRouter(lock: lock, controller: self)
     }
 
@@ -215,3 +216,11 @@ public class LockViewController: UIViewController {
     }
 
 }
+
+// MARK: - UIAdaptivePresentationControllerDelegate
+
+extension LockViewController: UIAdaptivePresentationControllerDelegate {
+    public func presentationControllerDidDismiss(_ presentationController: UIPresentationController) {
+        self.lock.observerStore.dispatch(result: .cancel)
+    }
+}