Allow login_hint to be passed for Google OAuth2

[bradvogel]

See the login_hint option in https://developers.google.com/accounts/docs/OAuth2Login. I need this option because my app already knows who the user should be logged in as and this will be a convenience for the user. I'd like Meteor.loginWithGoogle supported passing this in, e.g.

Meteor.loginWithGoogle({
    requestPermissions: ...
    loginHint: <what my app would like to authenticate the user as>
});

Let me know if this looks OK and I can file a PR. Thanks!

[bradvogel]

Ping on this. I'll file a PR if it looks OK.

[estark37]

I would look at a PR for this. For maximum appeal, I'd suggest that you unify this with the existing userEmail option, which is used for Meteor developer accounts. Perhaps there could be a single options called loginHint, which can be the user's email address and is documented as working with Meteor developer accounts and Google only. (Though of course we should maintain backwards compatibility with the existing userEmail option.) Does that make sense? Thanks!

[estark37]

Closing this issue since it's a feature request; feel free to submit a PR.

[bradvogel]

Filed #2790. Thanks!

[bradvogel]

#5313