Distinguish between when the user declined the "Sign In" prompt or cancelled the flow in iOS

The issue https://github.com/FormidableLabs/react-native-app-auth/issues/565 suggests a way to differentiate between cancels from login failures.

But in iOS there are two types of cancellations in general:
1. when the user presses "Cancel" on the prompt, that is by declining to sign in itself which is before the browser flow is even started
2. when the user actually cancels the login flow or closes the browser

Is there anyway to distinguish between these two cases for iOS? For proper tracking purposes, I'd like to know when the user declines the prompt specifically.

Currently if you check the `error` as per suggested in [here](https://github.com/FormidableLabs/react-native-app-auth/issues/565#issuecomment-1036596709), both of these cases resolve to user cancellation which is based on this [-3 error code](https://github.com/openid/AppAuth-iOS/blob/e191b1beadf3041259652e6e464eaceff16e5fbb/Source/AppAuthCore/OIDError.h#L103).

Beginnen Sie mit der Prüfung der Diskussion zur Abbruchbehandlung in Issue 565 und des referenzierten Fehlercodes in AppAuth-iOS Source/AppAuthCore/OIDError.h. Ermitteln Sie, ob die beiden iOS-Abbruchpfade über die React Native bridge unterschiedliche Signale liefern; als abgeschlossen gilt die Aufgabe, wenn Aufrufer zuverlässig unterscheiden können, ob die Sign In-Eingabeaufforderung abgelehnt oder der Browser-Ablauf abgebrochen bzw. geschlossen wurde.

Vom Indexierungsmodell aus dem Issue-Text verfasst.