[FEATURE] Implement BedrockRerank[Pre|Post]ProcessFunction

[tkykenmt]

Is your feature request related to a problem?

Amazon Bedrock introduced Rerank model support. OpenSearch can invoke Rerank models on Bedrock by writing custom pre/post processing function, but pre-built function is good for performance.

• https://aws.amazon.com/about-aws/whats-new/2024/12/amazon-bedrock-rerank-api-accuracy-rag-applications/

What solution would you like?
Implement BedrockRerankPreProcessing and BedrockRerankPostProcessing based on existing processor functions as follows.

• https://github.com/opensearch-project/ml-commons/blob/main/common/src/main/java/org/opensearch/ml/common/connector/functions/preprocess/CohereRerankPreProcessFunction.java
• https://github.com/opensearch-project/ml-commons/blob/main/common/src/main/java/org/opensearch/ml/common/connector/functions/postprocess/CohereRerankPostProcessFunction.java

What alternatives have you considered?
A clear and concise description of any alternative solutions or features you've considered.

Do you have any additional context?
Add any other context or screenshots about the feature request here.

[ylwu-amzn]

@tkykenmt , Do you want to implement this ?

[tkykenmt]

@ylwu-amzn Yes, I'd like to implement this.

[ylwu-amzn]

@tkykenmt , we plan to release this in the coming 2.19 , code freeze January 28th, 2025 . Do you have enough bandwidth to implement this and merge before the code freeze date ?

[tkykenmt]

@ylwu-amzn
Thank you for following-up. I'm implementing it and will create PR before freeze date on 2.19.

[dblock]

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