feature: Bedrock batch inference

[donatoaz]

As a user I'd like to leverage Bedrock Batch Inference so that batch product onboarding is cost optimized.

Definition of Done (DoD): Batch product onboarding uses Bedrock batch inference

This is challenging because batch inference jobs take the prompts in jsonl (jsonline) format, which would require some major refactoring in the code for our application. However there is a clear potential benefit of slashing costs in half

Bonus: refactoring supports both styles of execution: on demand and batch