Notification for Event APS when application period is over

[lorenzdiener]

Creating events from time to time I might forget about the end of the application period. It would be really great to have an "action required" reminder as soon as the application period ends. With this reminder, I can manage applications afterwards and advertise the event if we still need more applicants.

Some considerations:

• do we need an opt-in/opt-out?
• if multiple events have the same application period end (date), should only one notification be sent (aggregated)?
• do we want to have a "when do you want to be reminded" option (globally or per event) - at the exact date / one day before / ...