Feat Support image URLs in tool outputs for Langchain::Assistant

[Eth3rnit3]

PR Description: Enhanced Tool Message Support with Image URLs

This PR updates the Langchain::Assistant module to allow tool messages to include optional image URLs alongside text content. Key changes include:

1. New image_url Parameter:

   • The submit_tool_output method now supports an image_url parameter for richer tool outputs.

2. Backend Adjustments:

   • Adaptations were made to ensure compatibility with various backends (Anthropic, Mistral AI, OpenAI).
   • Structured content formatting is now used consistently across implementations.

3. Expanded Test Coverage:

   • Tests were added to validate tool message handling with and without image URLs.

This enhancement enables more flexible and expressive outputs for tools, paving the way for improved user interactions.

[andreibondarev]

@Eth3rnit3 Thank you for your PR. Your thoughts on the below... ?

What if we modified this to:

content, image_url = tool_instance.send(method_name, **tool_arguments)

# Rename the method parameter from output: to content:
submit_tool_output(tool_call_id: tool_call_id, content: content, image_url: image_url)

Something else to think about is that we might want to support the base64 encoded image re-presentation in the future, something like:

        {
          "type": "image",
          "source": {
            "type": "base64",
            "media_type": "image/jpeg",
            "data": "/9j/4AAQSkZJRg...",
          }
        }

[Eth3rnit3]

Yes you're right @andreibondarev it's better this way, it's more implicit and avoids parsing what is output from the tool.

• Works with Anthropic
• Works with Mistral

Here's the error message for OpenAPI, which doesn't support:image_url in a message with the role: "tool"

OpenAI HTTP Error (spotted in ruby-openai 7.3.1): {"error"=>{"message"=>"Invalid 'messages[3]'. Image URLs are only allowed for messages with role 'user', but this message with role 'tool' contains an image URL.", "type"=>"invalid_request_error", "param"=>"messages[3]", "code"=>"invalid_value"}}