///preferredStatusBarStyle was not being called for the individual view controller due to
///the container controller(UITabBarController)
///not using `childForStatusBarStyle` to decide the status bar style of each of its child vc.
///With some changes in iOS 15 in deciding the status bar style
///(previously it was deciding it using the `StatusBarStyle` property defined in info. plist), 
///it is now a requirement to update the `childForStatusBarStyle` property
///in UITabBarController subclass
///References: https://sanzeevgautam.medium.com/preferredstatusbarstyle-not-called-in-swift-eefae1f10262, 
///https://stackoverflow.com/a/19513714/3632958

override var childForStatusBarStyle: UIViewController? {
  return selectedViewController
}