Feature: add Bedrock Agents as a new model interface

[massi-ang]

Currently the chat can use either a langchain model interface or idefics model interface. langchain model interface uses the selected LLM as foundation model for a Langchain Conversational or ConversationalRetriever chain depending on a RAG workspace being selected or not. idefics is triggered only by the selection of Idefics multimodal FM and allows to chat with an image.

This feature is about adding a new bedrockagent model interface to be able to chat via a Bedrock Agent.
To start with, since there is currently no support for Bedrock Agents in CloudFormation and CDK, Bedrock Agent are setup independently of the solution and only referred to during the setup.
Depending on the timelines for CloudFormation support, we might evaluate the need to create a custom resource.

See https://docs.aws.amazon.com/bedrock/latest/userguide/agents.html for more information about Bedrock Agents.

[michaelhsieh42]

Does this help? https://github.com/aws-samples/amazon-bedrock-samples/tree/main/agents/bedrock-agent-cdk

[massi-ang]

Thanks Michael, this feature is already availble in the fear_bedrock_agent branch