Multifactor Authentication Support

[jleandroperez]

Description:

Whenever an account has Multifactor authentication enabled, right now, the app just displays an overlay with an error message.

Let's update the UX, so that, whenever needed, a new field requesting the One Time Password shows up.

Mockup:

[jleandroperez]

Update:
This issue requires #1220 to be addressed first.