CALENDAR: Add an option to prevent users from canceling appointments and events

Affected user(s):
Admins who need to monitor appointments and ensure changes are made only with their approval.

Task affected:
Ensuring that not all users can cancel appointments.

Impact:
Admins must search through canceled appointments to identify who changed the status.

Current state:
All users with access to the CALENDAR tab can cancel appointments and events.

Competition consideration:
N/A