guardrail keys update and guardrail support in streaming

[will-gao42]

Hi,

I wanted to extract guardrail traces in my application using the streaming function. This is what I hacked together to achieve that.

• It fixes the keys used to extract guardrail intervention result and guardrail trace
• It allows the trace to be passed from bedrock response back to the run_manager

I understand this is not ready-to-go, and I want to provide something for you to work with anyway.
Thank you!