Update FxA email link and give results for verified account info

Retrieve all accounts in the account info view but only list `'firefox-accounts'` or `'unknown'` as the source.

Update the FxA preverified email to send the user to sign up and prefill the email address.
I'm not crazy about this test. It fails every time you make a change to the preverify token code and the only solution is to copy/paste the new result here.