title: UIStackView adjust height to subviews
body: <p>I want the UIStackView to resize to fit their subviews (UIImageView and UILabel in this case)</p>
  
  <pre><code>    let headerView = UIStackView()
      headerView.axis = .vertical
      headerView.alignment  = .center
      headerView.distribution = .equalSpacing
      headerView.spacing = 10
  
      let headerImage = UIImageView(...)
      headerImage.contentMode = .scaleAspectFill
      headerImage.clipsToBounds = true
      headerImage.frame = CGRect(x: 0, y: 0, width: tableView.frame.width, height: tableView.frame.width / 1.618)
  
      let desciptionView = UILabel()
      desciptionView.text = "Some very long text wrapping multiple lines..."
      desciptionView.numberOfLines = 0
      desciptionView.font = UIFont.preferredFont(forTextStyle: UIFontTextStyle.body)
  
      headerView.addArrangedSubview(headerImage)
      headerView.addArrangedSubview(desciptionView)
  
      print(headerView.bounds) // always 0,0,0,0
      print(headerView.frame) // always 0,0,0,0
  
      tableView.tableHeaderView = headerView
  </code></pre>
  
  <p>(in this code height and width are 0)</p>
  
  <p>How to implement the wanted behaviour?</p>