[PYTHON-4342] Adds Hybrid and Full-Text Search to MongoDBAtlasVectorSearch

[caseyclements]

Description

This pull request adds Hybrid and full-text search to `MongoDBAtlasVectorSearch

No llama_index issue, but our internal ticket is PYTHON-4342

New Package?

No.

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes
• No

Type of Change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Added new unit/integration tests

In addition to adding unit/integration tests for the new features, the instructions to run against one's own version of Atlas are described in the README. We also run overnight CI workflows against llama_index's main branch (with a running cluster and openai_api_key) to ensure our changes or within pymongo do not break anything.

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods

[logan-markewich]

Huge update! Looks great though