Force UIModalPresentationFullScreen on iOS 13

Author: Rad Azzouz

ios/Classes/PspdfkitPlugin.m

@@ -62,6 +62,7 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
         }
 
         UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:self.pdfViewController];
+        navigationController.modalPresentationStyle = UIModalPresentationFullScreen;
         UIViewController *presentingViewController = [UIApplication sharedApplication].delegate.window.rootViewController;
         [presentingViewController presentViewController:navigationController animated:YES completion:nil];
         result(@(YES));