2FA: Show code during setup

The Authy and Bitwarden desktop apps don't support QR codes. So I need the actual code during setup to be able to set it up on a desktop.

As a workaround, you can do the following to get the manual code:

• Download a QR app on your phone that gives you the referenced URL. I used QR Reader on iPhone.
• Scan the QR code you get during Notejoy's 2FA setup with the app.
• The URL you will get will have the following form otpauth://totp/Notejoy:[user email]?secret=[manual code]&issuer=Notejoy.
• Take the [manual code] in the URL and use it as the manual code in your authenticator app.