Adding CopilotKit/AG-UI to AgentCore CLI

### Description

As per this [sample starter](https://github.com/aws-samples/sample-FAST-applications/tree/main/samples/copilotkit-generative-ui)
and the following [doc](https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/runtime-agui.html)
CopilotKit and AG-UI now works with AgentCore for LangGraph and AWS Strands.

The suggestion is to add this to the AgentCore CLI, so developers are able to scaffold a fully working app with minimal effort.
Currently the suggestion would be on creating a minimal frontend that hooks up to the agent and has basic chat. The sample linked above can then be used as an example of what code can you grab to add more functionality

### Acceptance Criteria

- Users are able to scaffold LangGraph + CopilotKit frontend being AWS infrastructure
- Users are able to scaffold AWS Strands + CopilotKit frontend being AWS infrastructure

### Additional Context

_No response_