This implements Webauthn. Old devices can be used to authenticate via the appid compatibility layer which should be automatic. New devices will be registered via Webauthn, and devices which do not support FIDO2 will no longer be able to be registered. At this time it does not fully support multiple devices (backend does, frontend doesn't allow registration of additional devices). Does not support passwordless.
Adds encryption to the U2F public keys. While the public keys cannot be used to authenticate, only to validate someone is authenticated, if a rogue operator changed these in the database they may be able to bypass 2FA. This prevents that.
Allow users to configure the TOTP Algorithm and Digits. This should be used with caution as many TOTP applications do not support it. Some will also fail to notify the user that there is an issue. i.e. if the algorithm in the QR code is sha512, they continue to generate one time passwords with sha1. In addition this drastically refactors TOTP in general to be more user friendly by not forcing them to register a new device if the administrator changes the period (or algorithm).
Fixes#1226.
