Confirmable 2FA

[taylorotwell]

This PR allows 2FA to be configured to require confirmation before it is fully enabled via a new feature option. I don't think this PR is even required to be breaking with a few additional tweaks. But, sending to master for now.

Enabled via:

Features::twoFactorAuthentication(['confirm' => true])

[driesvints]

I feel like we should be able to do this in Fortify v1. By default Features::optionEnabled(Features::twoFactorAuthentication(), 'confirm') will return false so it should not break any existing apps.

However, in Fortify 2.x I would set it to be enabled by default.

[CyberPunkCodes]

A very necessary PR to make Fortify usable with real-world customers 👍

Thank you very much for this. I haven't tested it, but so long as it works as advertised, it will make Fortify and it's children (Breeze, Jetstream, etc) complete!

[taylorotwell]

#358