Student Applications - Add the ability to send reminders to applicants that have not yet accepted or declined lottery placement offers and set a deadline

Now that schools can send notifications to students to allow them to Accept or Decline their spot based on lottery results, schools need to be able to send reminder emails. Ideally, we could allow this to be done automatically as other notifications are currently sent, but we’d need to add a setting to define a deadline for acceptance and then stop sending reminders after that date/time.

After the deadline passes, this should also automatically mark all pending offers still remaining as Declined. Additionally, at that time, the declined offers should be counted and that same number of waitlisted applications should be marked as pending (starting with the lowest ranked).