Allow possibility to disable face unlock on Android

[eblis]

It would be nice if you could select which authentication methods are allowed, at least on Android systems. Some Android vendors allow both fingerprint and face unlock, but certain sensible applications, like Bitwarden shouldn't allow login via face, just by fingerprint.

An option in the code to select if you want strong authentication (fingerprint) or weak authentication (face) would be very nice.

This is a very requested feature in Bitwarden and as far as i can tell Bitwarden uses this plug-in for cross platform authentication.