fix(iOS): unregister tabs accessory observer from observed wrapper#3948

kligarski merged 2 commits intosoftware-mansion:mainsoftware-mansion/react-native-screens:mainfrom

safaiyeh:fix/tabs-bottom-accessory-kvo-invalidationsafaiyeh/react-native-screens:fix/tabs-bottom-accessory-kvo-invalidationCopy head branch name to clipboard