Fix: ChromaVectorStore can attempt to add in excess of chromadb batch…

[Brad-Edwards]

… size

Description

Changed ChromaVectorStore.add to batch inputs at one less than chromadb's max to avoid the oversize error. Adds a class method to do chunking.

Fixes #7648

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

I have passing unit tests on my branch but have not included them. The unit test to add a large number of nodes takes ~5 secs to run. If that's acceptable, I can submit the unit tests for add

I noticed tests were missing for all of the llama_index.vector_stores.chroma.py. So I also implemented tests for several other methods.

Let me know if you want all the unit tests, all the tests excluding add, or none of them.

• [see above] Added new unit/integration tests
• I stared at the code and made sure it makes sense

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• [N/A ] I have made corresponding changes to the documentation
• My changes generate no new warnings
• [see above] 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