Add concept of resident district

Summary of outcomes for Data Standard 3.2

• Problem Addressed: There is not a defined way to identify a student's resident district.
• High-level Reasoning: There is a need to define a resident district for a student that is not necessarily tied to the school where the student is enrolled. Initial discussion was around a new element but it was decided that the StudentEducationOrganizationResponsibilityAssociation is a better fit with a new Responsibility descriptor value.
• Changes Made: Added "Residency" to the Responsibility descriptor value set.

Original ticket description follows:

Several states have added the concept of "resident district" and we have also seen this concept needed elsewhere (OR Nexus project).  This looks like an opportuntiy to standardize capture of this concept. 

Two out of three states created an extension to capture the resident district id in StudentSchoolAssociation extension.

WI - Resident District Concept

Use Case Documentation - https://dpi.wi.gov/wise/data-elements/district-of-residence
Implementation Details - This is an extension to SEOA

NE - Resident District Concept
https://cdn.education.ne.gov/wp-content/uploads/2019/12/ADVISER_Data_Elements_20192020_V4.2.pdf

This is an extension to StudentSchoolAssociation

AZ - Resident District Concept
This is an extension in StudentSchoolAssociation

None of the states so far have used 'StudentEducationOrganizationResponsibilityAssociation'. AZ released AZEDS 6.0 version of the API last week Jan 23 2020. They are starting to use the StudentEducationOrganizationResponsibilityAssociation to capture the resident school id for with the responsibility being 'IEP'.
Other states don't use StudentEducationOrganizationResponsibilityAssociation.