TEST_ DO NOT MERGE - Add Cosmos DB query translation and collection navigation tests

[SamMonoRT]

Added test coverage for:

• Collection navigation with Skip/Take operations
• Complex aggregations in projections and subqueries
• Math and string function translations
• Query translation edge cases

• I've read the guidelines for contributing and seen the walkthrough
• I've posted a comment on an issue with a detailed description of how I am planning to contribute and got approval from a member of the team
• The code builds and tests pass locally (also verified by our automated build checks)
• Commit messages follow this format:

        Summary of the changes
        - Detail 1
        - Detail 2

        Fixes #bugnumber

• Tests for the changes have been added (for bug fixes / features)
• Code follows the same patterns and style as existing code in this repo

[roji]

@SamMonoRT trying out AI generation of tests? :)

[SamMonoRT]

Closing this draft PR.