ios: Tapping a notification doesn't bring you to the conversation (app open in foreground or background)

I've noticed a bug lately where I tap a notification on iOS and it doesn't take me to the relevant conversation. It's only active when the app is open (in the foreground or background).

We've done some investigation and have a draft fix, which happily means using less of `@react-native-community/push-notification-ios` instead of more. 🙂