Fix MistralAIMessage to handle "Tool" Output

[dkaplan88]

Solves: #839

Breaks up hash by specific role following API Conventions

https://docs.mistral.ai/api/#tag/chat/operation/chat_completion_v1_chat_completions_post
Assistant

System

Tool

User

[andreibondarev]

What're your thoughts on doing something like this:

def to_hash
  if assistant?
    to_assistant_hash
  elsif tool?
    to_tool_hash
  ...
end

def to_assistant_hash
  h = {
    role: role,
    content: to_content
  }
  h[:tool_calls] = tool_calls if tool_calls.any?
  h
end

[andreibondarev]

It's pretty similar to what you've got just slightly different stylistically.

[dkaplan88]

Hmm, I am very on the fence about it as one hash or hash by role.

I think declaring the separation by role makes sense since it feels like Mistral has declared separate API Contracts by role (as we see with content) 😄

I updated it to do it by role and refactored the content hash so it was just building the array value.

[andreibondarev]

@dkaplan88 Thank you! Great work!