feat: AmazonBedrockEmbeddingFunction support for Cohere Embed models

[JGalego]

Description of changes

• New functionality
  • Adds support for Cohere Embed models to AmazonBedrockEmbeddingFunction

Test plan

How are these changes tested?

• Tests pass locally with pytest for python

Also, manually tested with python:

>>> import boto3
>>> from chromadb.utils.embedding_functions import AmazonBedrockEmbeddingFunction
>>> session = boto3.Session()
>>> bedrock = AmazonBedrockEmbeddingFunction(session=session, model_name="cohere.embed-multilingual-v3")
>>> bedrock(["Hello World", "Olá Mundo"])
...

[github-actions]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• Can you think of any use case in which the code does not behave as intended? Have they been tested?
• Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• If appropriate, are there adequate property based tests?
• If appropriate, are there adequate unit tests?
• Should any logging, debugging, tracing information be added or removed?
• Are error messages user-friendly?
• Have all documentation changes needed been made?
• Have all non-obvious changes been commented?

System Compatibility

• Are there any potential impacts on other parts of the system or backward compatibility?
• Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[JGalego]

@beggers reaching out to you b/c you were the last one to review+approve+merge changes to utils/embedding_functions.py (#1517). Can we find a reviewer for this one?

[atroyn]

Please also update the embedding model documentation: https://github.com/chroma-core/docs/blob/main/docs/embeddings.md

Currently the AmazonBedrockEmbeddingFunction is missing from the docs entirely.

[JGalego]

Please also update the embedding model documentation: https://github.com/chroma-core/docs/blob/main/docs/embeddings.md

Currently the AmazonBedrockEmbeddingFunction is missing from the docs entirely.

There's an open PR from another contributor for the docs - chroma-core/docs#204

[chezou]

I've been waiting for the review for JS implementation as well #1659

[tazarov]

A few nits.

[JGalego]

@tazarov any other changes?

[jeffchuber]

Our underlying impl has changed and so this PR is not landable as is.

That being said - we'd still like to add this functionality and that is now tracked in this issue.