Add support in the Grade Domain for Standards Base Grading

Summary of outcomes for Data Standard 3.2

• Problem Addressed: Need a way to align grades with learning standards.
• High-level Reasoning: WY has an extension model that allows a collection of learning standards to be referenced on a Grade that meet the use case requirements. This was used as the basis for the model updates.
• Changes Made: Created a LearningStandardGrade common that includes LetterGradeEarned, NumericGradeEarned, DiagnosticStatement, and PerformanceBaseConversion. This is added to Grade as an optional collection.

Original ticket description follows:

Issue: The current Grades/Grading Period resources do not effectively align with reporting grades for standards. There are thousands of standards and it is not efficient for LEAs to map every standard to a Grading Period to report.

This model will need to support both 1 time standards (ie: Student learns to count to 10) as well as standards that are graded multiple times in the school year.

Attached is a few samples of Standards Based Report cards to show different ways of reporting grades for standards.