FI-1928 Fix generator bug for Reference choice

[yunwwang]

Summary

This fix Github Issue https://github.com/onc-healthit/onc-certification-g10-test-kit/issues/412

What changes:

• Fix the name [:type] to [:types] in must_support_extractor
• Re-generate US Core v4 and v5

Testing Guidance

Visual inspect medication_request/metadata