Web Authentication API support

[CetinSert]

https://developer.mozilla.org/en-US/docs/Web/API/Web_Authentication_API

1. Is this new authentication API easy to integrate into authn-server?
2. Is there any work happening on this front?

@cainlevy

[cainlevy]

I'd love to support this in AuthN! I believe https://github.com/duo-labs/webauthn would be a good starting point to plan an integration.

One thing I'm presently unclear on is whether the user record must be created at the beginning of the challenge process. That could require light refactoring to support, because it would introduce a new "unregistered" user state that other features must consider.

I'm also uncertain how large the final credential package will be. It may require a new database field for storage.