Authenticate with an external provider

[kchudy]

Description

As a user, I want to authenticate with an external provider (e.g. Google) when connecting to an MFA-protected location.

AC:

• When connecting to a location that requires OpenID-based MFA, show a "Two-factor authentication" modal
• Provide a branded "Authenticate with Google" button that opens the browser for the OAuth flow
• Offer a "Don't show this screen next time" checkbox to bypass the modal for subsequent connections