[Feature Request] Finalize 2FA implementation

[matoszz]

We've implemented some basic functionality around OTP code generation and storage, but need to finish 2FA constructs such that:

• The user can both enable and disable 2FA or select different mechanisms to perform 2FA
• We generate a barcode and can display the barcode to add utilities such as google authenticator
• We have webfinger endpoints or similar functionality that allows for us to know during the login flow if the user has enabled 2FA or not
• The user is able to download their recovery codes and we check for the use of one of the recovery codes during login