[FEATURE] Add default process functions for bedrock embedding and cohere rerank model

[ylwu-amzn]

Now we have default pre/post process functions for openai and cohere embedding models. Suggest also add default process functions for bedrock embedding model to avoid the complex pre/post process function of painless script.

In 2.12 we have reranks search feature, to support this, we should also add default process functions for cohere rerank model.

[ylwu-amzn]

Add default process function for cohere rerank model https://github.com/opensearch-project/ml-commons/pull/1954