Automatically move customers back to waitlist

Often, with low-quantity restocks, several who asked for BIS alerts lost out on getting the product. And, since they've received an email, they're no longer on the list for a BIS alert when the product comes back in stock.

Seems like Rocket could track which of the BIS alerts resulted in a purchase, then reset the others who missed out to be back on the waiting list. Or, gives us a Reset button next to the resend button so we can manually re-add someone to the waiting list who missed out buying via the BIS alert email.