partners[chroma]: add retrieval of embedding vectors (#28290)
This PR adds an additional method to `Chroma` to retrieve the embedding
vectors, besides the most relevant Documents. This is sometimes of use
when you need to run a postprocessing algorithm on the retrieved results
based on the vectors, which has been the case for me lately.
Example issue (discussion) requesting this change:
https://github.com/langchain-ai/langchain/discussions/20383
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Co-authored-by: ccurme <chester.curme@gmail.com>
