title: How to unmount screen on blur in a StackNavigator?
body: <p>Im using <strong>React Navigation x5</strong>, I have <code>StackNavigator</code> that's loading bunch of screens. I want to unmount one particular screen component on blur to get the same result of using <code>unmountOnBlur</code> when using a <code>DrawerNavigator</code>.</p>
  <p>How can I achieve that?</p>