Yahoo account recovery page with headless navigator

[amaury1093]

Problem

We cannot check yahoo emails via direct SMTP connection, so until today, we use a Yahoo API check to do this. However, it's flaky (see #1308), so we need a more robust solution.

Solution

Similarily to what's done with Hotmail, use a headless navigator to connect to yahoo's account recovery page https://login.yahoo.com/forgot to check if an email exists or not.

Advantages:

• Should be less flaky that the Yahoo API
• Able to check disabled accounts How to check if yahoo emails are disabled or not #473

1. Existing account

Got redirected to a new page

2. Non-existing account

3. Disabled account

Got redirected to new page