Toggleable VPN detection

[prettyflowerss]

As of right now, there is no VPN detection, but there's alt detection.

There's currently two flaws with this:

• Alt detection may false flag if multiple people ever so happen to use the same VPN server.
• Alt detection will be rendered useless if they can just turn on a VPN.

I originally decided against adding VPN detection to the beta, because the goal of Keycard is to be insanely user friendly and secure; so people don't have to turn off their VPNs.

However, this won't work well for actual security, I recommend it being a toggleable setting.