* Add comprehensive API polynomial subresultants tests
- Add tests for Z3_polynomial_subresultants function in api_polynomial.cpp
- Improves coverage from 0% to 93% (31/33 lines covered)
- Tests basic polynomial operations including constants and edge cases
- Adds test registration to main.cpp and CMakeLists.txt
* staged files
* remove files
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Co-authored-by: Daily Test Coverage Improver <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Nikolaj Bjorner <nbjorner@microsoft.com>
