2 factor authentication for SaaS template

[hansalves]

I've been playing around with the SaaS template for a bit and have implemented a 2FA login flow using totp-rs. A working proof of concept can be found here.

I think this might be a good feature to add to the template by default.

However, this is the first time I did anything like this, so it might be a good idea if someone could review the code. There are also a couple of points that will require improvement, with which I might require some assistance before creating a PR.

So, is there any interest in adding this?

Kind regards,
Hans