fix: web3 account google login with email already used as main email by another account

[blushi]

Description

Closes: #425

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[blushi]

I'm confused as to why we want to allow this. If someone has account A with that email, why should we let them connect to a different web3 account with the same email but via google instead of email? This seems like something we should disallow.

This is just a consequence of the fact that we let users have a google email that could be different from the main email (used for logging in via OTP) cc/ @erikalogie

[blushi]

closing per discussion during the architecture call, we should instead have uniqueness across Google email and main email and when connecting to google, set main email to google email.