Adds a second factor landing page that centralizes a user's second factor configuration.
This contains both TOTP and Backup, and also allows multiple TOTP tokens to be registered and organized by a name. Access to this page is authenticated via password, and cached for 30 minutes via a secure session.
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
Jeff Wong
Sam Saffron
Guo Xiang Tan
Maja Komel