Assignment and Lesson create override data generators should update calendar events

Discovered while peer reviewing MDL-76049.

When a override is created for Lesson or Assignment on the UI, the *_update_events() function is called to update the related override calendar events. However that behavior is not mirrored in the create_override data generators for those modules, the override data is inserted in the table but the calendar events are not updated.

Since quiz now update calendar events when a override is created using data generators, we should do the same for the other two modules that supports overrides (Lesson and Assignment)