ResearchStudy.Focus: Inconsistencies b/t dbGap, KidsFirst and AnVIL

[bwalsh]

Not all ResearchStudies have a populated focus

Tests implemented here

• test_AggregatedResearchStudy_Focus: AssertionError: 421 of 422 ResearchStudies missing Focus codeable concepts

  • test_KidsFirstResearchStudy_Focus: AssertionError: 28 of 29 ResearchStudies missing Focus codeable concepts

  • test_AnvilResearchStudy_Focus: AssertionError: 393 of 393 ResearchStudies missing Focus codeable concepts

• test_dbGapResearchStudy_Focus: AssertionError: 166 of 1857 ResearchStudies missing Focus codeable concepts