Unify Concept of Version in Data Model

Summary of outcomes for Data Standard 2.1

• Problem Addressed: The common simple type Version erroneously suggests a formal Ed-Fi version type.
• High-level Reasoning: This common simple type was created to support Assessments and is not related to the Ed-Fi version type.
• Changes Made: Renamed the common simple type (shared integer) Version to AssessmentVersion; Updated reference to Version in the Assessment domain entity to reference AssessmentVersion

Original ticket description follows:

Suggest unifying the concept of versions between assessment versions and content standard versions. Currently assessments use an integer for version data and content standards use a string. Unifying would allow a common simple type of Version and then add context information to differentiate the entity being versioned.