title: Window.MakeKeyAndVisible() is not showing new window in iOS 13 and above OS
body: <p>My requirement is to open new UIWindow instead story board.
  Used below code to do this,</p>
  
  <pre><code>UIWindow window = new UIWindow(UIScreen.MainScreen.Bounds);
                  UIApplication.SharedApplication.KeyWindow.WindowLevel = UIWindowLevel.Normal + 0.1f;
  
                  window.RootViewController = new MainNavigationController();
                  window.MakeKeyAndVisible();
  </code></pre>
  
  <p>It's working fine in iOS below 13 versions, but not in 13 and above.</p>
  
  <p>Have noted that iOS 13 and above were new update for multi screen, and have introduced scene delegate, so need to move all app delegate stuffs to scene delegate. But in my case there is no code stuff in app delegate and opening this window after my launch screen story board.</p>
  
  <p>is it really required to add scene delegate in existing application? if so how to properly integrate scene delegate in existing application in xamarin iOS?</p>