Google Calendar Event Update with Access Level Changes

[ryantrinh05]

Updates the Event.save() method to handle the cases when access level changes during edits to an event.

Previously, the method would try to update a GCal event on the new calendar (e.g. Candidate Google Calendar) using the event id specific to the old calendar (e.g. Internal Google Calendar), resulting in no changes.

This PR addresses this by first checking if the access level changes in the update:

• If it doesn't, it updates the GCal event the same.
• If it does, it deletes the old GCal event and creates a new one in the new calendar, linking the new google_calendar_id to the Event model.