FI-1711 Fix the failure when target_profiles is nil

[yunwwang]

Summary

This is to fix Github Issue (https://github.com/onc-healthit/onc-certification-g10-test-kit/issues/261)

reference_resolution test failed to handle v3.1.1 profiles without target_profile choices.

Changes include

• Add & to handle the choices hash without target_profiles key
• Add unit test to simulate the failed test mentioned in the GitHub Issue

Testing Guidance

All unit tests passed