Added button to remove password from account if user has a linked
external account or passkey
The button only displays if the user has at least one associated account
or a passkey set up. Uses the ConfirmSession dialog in addition to a
warning about deleting the password.
Users can still reset their password via the Reset Password button
(which will now display "Set Password" if they've removed it).
Also prevent user from removing their last remaining associated account
or passkey if they have no password set.
Replaces PR #31489 from my personal repo, with some fixes for conflicts
since then.
Adds 2 factor authentication method via second factor security keys over [web authn](https://developer.mozilla.org/en-US/docs/Web/API/Web_Authentication_API).
Allows a user to authenticate a second factor on login, login-via-email, admin-login, and change password routes. Adds registration area within existing user second factor preferences to register multiple security keys. Supports both external (yubikey) and built-in (macOS/android fingerprint readers).
