title: Make a local calendar's title not editable
body: <p>I am using the calendar plugin(<a href="https://ionicframework.com/docs/native/calendar/" rel="nofollow noreferrer">https://ionicframework.com/docs/native/calendar/</a>) to access the native calendar on iOS (iPad specifically). 
  At the moment, I have no problem in setting up a custom calendar, specifying a name(calling the createCalendar method), or with the creation of events on it. What I would like to achieve, though, is to create a custom calendar which contains editable events but which is NOT editable in terms of its name. 
  I have searched on the apple developers documentation (<a href="https://developer.apple.com/documentation/eventkit/ekcalendar?language=objc" rel="nofollow noreferrer">https://developer.apple.com/documentation/eventkit/ekcalendar?language=objc</a>) and what I have found is that the "immutable" property should do the trick; meaning that if set to YES, this property should allow to add, delete and modify events on my calendar but should also deny editing the specific calendar from the native ios calendar app. 
  The issue is that this property seems not to be settable (it is read-only). 
  Can you please guide me on how to set it or on how to make the title attribute not editable from the native ios calendar app (like the holidays calendar)? </p>