feat(test): Add more functional tests!

@zaach or @vladikoff - r?

* Add functional tests to check users who verify by replacing the original tab, and users who verify by closing the original tab and open a new tab. This is for both OAuth and Sync, for sign up and reset password.
* Add a functional test for signing into sync with an unverified account

fixes #1935
issue #1816
issue #1936
issue #1938
issue #1940