Force email verification as part of the user signup process

[arinoch]

What

As part of account creation, and especially before allowing users to create a site (specifically on a trial plan), enforce a requirement that email must be verified.

Why

This is a known vector for fraud (p1715769804550359/1715767859.100399-slack-CDJ9Z349W), as well as a significant account security risk (#52193, p58i-bwV-p2). With the advent of Woo Express trials, this has become significantly more of a concern for both the Account Recovery team and our fraud team.

How

No response

[mrfoxtalbot]

Thank you for opening this, @arinoch!

I have shared this here p1715942707680399-slack-C048CUFRGFQ to ensure it gets reviewed quickly.

Related: #90740

[arinoch]

Thank you, @mrfoxtalbot!

Adding pbMDNC-1od-p2 as additional context.

[Jaykame]

Thanks for adding this @arinoch.

I also wanted to add this pbMDNC-1ms-p2 as an additional reference for this request.

[Jaykame]

Another case to reference pbMDNC-1oZ-p2.