Add date history to Course domain entity

Current recommendation is to add School year to the key. See detailed comments in DATASTD-797

Info from UDM Dates Analysis:
Recommendation: Track BeginDate (optional) and EndDate (optional) at the entity level

Use Case/Benefit:
Vendors must be able to tie a course offering to a valid and current Course that is part of the State’s or District’s course catalog for the current School Year. Adding a date(s) to the Course object would make the courseOffering to course association more straightforward, less prone to error by selecting historical course.

We are suggesting that course dates be optional per the standard, and that implementations can require them should they have a need to track historical course records? We would like feedback on this approach.

Alternate implementation options:

1) Add a begin date to the key, and require it, leave end date optional

2) Add School year to key

3) Forego dates and add a status element to determine whether course is valid/current