Expanded `PublicKeyCredentialCreationOptions`

[Joride]

Hey folks,

This might be a change that brings changes to clients using the library, so please review carefully. Maybe this one requires a version-change? We could opt to maintin existing behaviour, although I would be careful with that option as well, as effectively clients are currently using an incomplete implementation of the spec? Open to hearing what direction to take and adjust as necessary.

I added some code so the options returned from beginRegistration now contain more fields from the spec. Without these changes, I noticed that on Android, passkey-authentication could be used, however, after signup, the passkey did not seem to be stored anywhere. And so if a user was logged out, they could not sign in again with the created passkey.

With these changes, that issue is now resolved.