New semanticsearch env

[cdreetz]

Description

Add new base semantic search env so that any semantic search related env can extend just by adding a corpus processing method, corpus dataset, and corresponding QA dataset

Type of Change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation update
• [ ] Test improvement

Testing

• [x] All existing tests pass when running uv run pytest locally.
• [ ] New tests have been added to cover the changes

Checklist

• [ ] My code follows the style guidelines of this project as outlined in AGENTS.md
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] Any dependent changes have been merged and published

Additional Notes