Prior to this patch, if a user was in two groups, and an override
existed for both groups in an assignment the override
visually lower on the override list would be displayed on the
overview, whereas the one visually higher would be displayed
in the assignment grading table.
* Move and rename \core_calendar\local\api::get_legacy_events() to
calendar_get_legacy_events() in calendar/lib.php.
* Fix the parameter-normalising callback function in
calendar_get_legacy_events() so that it correctly handles false values
by returning an empty array instead of it returning a non-empty array
that contains an empty element.
This function was moved to local_api::get_legacy_events.
Also removed the calendar/classes/api.php file since it no longer contained any
functionality and added unit tests for local_api::get_legacy_events (a copy of
the unit tests for calendar_get_events).
Part of MDL-55611 epic.
Michael Hawkins