Add route to edit event details

[asmahood]

Description

Executive members cannot edit the details of an event after it is created. If there are any errors in the event, a super admin needs to enter the database in order to fix these errors.

Add both an API endpoint + new edit page for events. The API endpoint should be respond to

// PATCH /events/<eventId>
// Not all arguments needed, only items that are being changed
{
  "name": "...",
  "format": "...",
  "notes": "...",
  "startDate": "..."
}

Note: An event should not be editable after it has ended. Respond with a 403 in this case.