Remove AcademicWeek

There is no evidence that AcademicWeek is in use in any current Ed-Fi-based integrations. In addition, the definition describes the entity as optional: "This entity represents the academic weeks for a school year, optionally captured to support analyses." The entity does not seem to be solving actual problems in field usage.

The proposed action would be to deprecate the entity to signal that it is a candidate for future removal.