R1:e090b32c7528

Add a rate limit to requesting account recovery links from a given remote address

Summary:
Depends on D20666. Ref T13343. In D20666, I limited the rate at which a given user account can be sent account recovery links.

Here, add a companion limit to the rate at which a given remote address may request recovery of any account. This limit is a little more forgiving since reasonable users may plausibly try multiple variations of several email addresses, make typos, etc. The goal is just to hinder attackers…