Support for SageMaker Endpoints as a ChatModel

[bigbernnn]

SageMaker Endpoints are currently only handled as an LLM. This introduces additional steps and a lot of complexity to integrate them within an agentic setup on LangGraph. SageMaker Endpoints should be accessible like Bedrock through a ChatModel as such:

llm = ChatBedrock(
    model_id="anthropic.claude-3-sonnet-20240229-v1:0",
    region_name="us-east-1"
)

To validate functionality, ChatSageMakerEndpoint should be a stand-in replacement for ChatBedrock in a LangGraph StateGraph.

Tasks

• ChatSageMakerEndpoint implementation, provides basic invoke feature
• Streaming support
• Function calling with tools support

[3coins]

@bigbernnn
Agree with your proposal. Do you want to take a first pass at it and submit a draft PR?

[bigbernnn]

Happy to!

[rsgrewal-aws]

ChatBedrock cannot and should be used for SageMaker endpoints. Let us create a ChatSageMaker class and go with that

[bigbernnn]

Agreed

[bigbernnn]

@3coins #368. As mentioned in the description, other non-blocking components that should follow in other PRs:
- Support for streaming
- Support for function binding