Add race and ethnicity bindings to bindings collection

[bryantaustin13]

Issue #433 QI Core Value Set and Code System Query Issue Description

visitExtensions was added to StructureDefinitionElementBindingVisitor to visit the extensions and collect the bindings especially for patient.extension:race and patient.extension:ethnicity.

• Github Issue:
• [X ] I've read the contribution guidelines
• [ X] Code compiles without errors
• [ ] Tests are created / updated
• [ ] Documentation is created / updated

By creating this PR you acknowledge that your contribution will be licensed under Apache 2.0

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 90 lines in your changes missing coverage. Please review.

Project coverage is 21.85%. Comparing base (7a04aaf) to head (c433981). Report is 1 commits behind head on master.

Files	Patch %	Lines
...rkit/StructureDefinitionElementBindingVisitor.java	0.00%	77 Missing :warning:
...s/cqf/tooling/operation/ProfilesToSpreadsheet.java	0.00%	12 Missing :warning:
...tooling/operation/QICoreElementsToSpreadsheet.java	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #531 +/- ## ============================================ - Coverage 21.91% 21.85% -0.06% - Complexity 1672 1673 +1 ============================================ Files 297 297 Lines 25317 25390 +73 Branches 3990 4005 +15 ============================================ + Hits 5548 5550 +2 - Misses 18848 18920 +72 + Partials 921 920 -1 ```

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