title: UIHostingController resets custom leftBarButtonItem when pushed
body: <p>I have a view controller in a navigation controller. In <code>viewDidLoad</code>:</p>
  <pre><code>let button = UIButton()
  button.setImage(Theme.Icon28.back.withRenderingMode(.alwaysTemplate), for: .normal)
  button.addTarget(self, action: #selector(didTapBackButton), for: .touchUpInside)
  button.imageEdgeInsets = Constants.buttonImageEdgeInsets
  button.accessibilityIdentifier = &quot;nav_btn_back&quot;
  
  navigationItem.leftBarButtonItem = button
  </code></pre>
  <p>This sets up my custom back button. Now I want to push a <code>UIHostingController</code>:</p>
  <pre><code>navigationController?.pushViewController(UIHostingController(rootView: SomeView()), animated: true)
  </code></pre>
  <p>With <code>SomeView</code> as:</p>
  <pre><code>struct SomeView: View {
      var body: some View {
          Text(&quot;Hello World&quot;)
      }
  }
  </code></pre>
  <p>Now when I push the <code>UIHostingController</code> the back button will change back to the default system back button, the <code>leftBarButtonItem</code> has lost my custom button. Has anyone else run into this issue?</p>
  <p>Why is it overriding my custom button?</p>