Add Highest Level of Education to Parent entity

Summary of outcomes for Data Standard 3.x

• Problem Addressed: There is no way to collect the Parent's highest level of education in the current model.
• High-level Reasoning: Tracking the parents highest level of education is becoming increasingly common. Also, by adding the "level of education common type" to Parent would promote more consistency between the Parent, Student, and Staff domain entities.
• Changes to be Made: Add common type LevelOfEducation to the Parent domain entity as an optional property

Use cases:

**So far I have identified 2 use cases where this is relevant. 

1. During the enrollment process of students it is useful to have the parent's highest level of education for statistics and promoting first generation college applicants.
2. Within the development of the Yes Prep parent portal this information is relevant to display the parents profile.