[2FA] Disabling and enabling two factor authentication should require the user's password.

[DarthShmev]

In order to enable or disable 2FA, a user should be required to input their password via a confirmation modal. This will prevent a user from accidentally enabling 2FA and not setting it up. Also, the user's password should be required to disable 2FA in order to prevent potential hijacking of an account.

My proposal is to have a similar flow as to logging out other sessions.

As always, feedback is welcome.

[yoeriboven]

It's probably better to actually enter the 6 digit code so we're sure 2FA is set up on the user's phone.

Also, this looks similar to #74.

[driesvints]

Duplicate for #74