Add support for Amazon Nova models

[tpaulshippy]

Purpose

Addresses #928

Approach

Add support for Amazon models in AwsBedrock and introduce AwsBedrockAmazonResponse.

Testing

Ran against Nova Micro.
RSpec

[mtrefilek]

@andreibondarev this is looking good to me. Are we able to get test runs going?

[Copilot]

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

lib/langchain/llm/aws_bedrock.rb:305

• Consider whether additional keys such as :top_p, :top_k, and :stop_sequences should also be removed after merging them into inferenceConfig to avoid potential duplication or inconsistencies in the parameters.

params.reject { |k, _| k == :max_tokens || k == :temperature }