moveEvent transfers an event between calendars visible to the same connected
account. It is for events the account organizes, not attendee copies.
Example
Inputs
destinationCalendar and event are required. sourceCalendar defaults to
primary. Calendar values accept exact visible titles or IDs; event accepts an
ID or standard event URL. sendUpdates is "all", "externalOnly", or
"none"; account selects the Google account.
Output
Returns the movedCalendarEvent with calendarId set to the destination; see Get event. Follow-up actions must use that destination calendar.