2FA - Allow for not trusting a device at login so it prompts every time

This could be solved by giving the option to trust a device when signing in with 2FA. It can be checked by default to mimic current behavior but give the user a choice instead of always implicitly trusting the device. If a user wants to sign in somewhere new or public but forgets to log out or gets pulled away, this could help protect the security. This could also be helpful when using family computers and want an extra prompt each time.