[Integration] AWS Bedrock Reranker

[SuperSecureHuman]

Description

AWS Bedrock now has rerankers (started with Cohere Reranker 3.5). This PR adds support for it.

https://aws.amazon.com/blogs/machine-learning/cohere-rerank-3-5-is-now-available-in-amazon-bedrock-through-rerank-api/

Type of Change

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

Added Reranker from AWS Bedrock

How Has This Been Tested?

Replaced example code from llamaindex to use the AWS Reranker, and made sure it works

[SuperSecureHuman]

Do let me know if anything is needed / modifications are needed

[SuperSecureHuman]

If this is good to go, I can add a sample notebook

[brycecf]

Real unit tests please. This is not a meaningful test:

def test_class():
    names_of_base_classes = [b.__name__ for b in AWSBedrockRerank.__mro__]
    assert BaseNodePostprocessor.__name__ in names_of_base_classes

[logan-markewich]

I agree with @brycecf -- net new packages should have meaningful tests. You can mock out the api calls to boto3/bedrock for example, or other strategies

[SuperSecureHuman]

Hi, I have tried using mock... Please lemme know if anything