R1:5dd489500155

Move "Password Reset" email to "PeopleMailEngine"

Summary:
Ref T13343. This makes "Password Reset" email a little more consistent with other modern types of email. My expectation is that this patch has no functional changes, just organizes code a little more consistently.

The new `setRecipientAddress()` mechanism deals with the case where the user types a secondary (but still verified) address.

Test Plan:
- Sent a normal "login with email" email.
- Sent a "login with email to set password" email by…