Add validateEmailConfirmationFromRequest method

[shafan]

In VerifyEmailHelper but not in the interface

[bocharsky-bw]

Thanks for this PR! We have a @method annotation for that validateEmailConfirmationFromRequest() in the interface, so that annotation should be removed. But first of all, that's done this way to avoid BC breaks. We can't change interfaces without making a major release because it would lead to BC breaks.