Convert structured prompts to structured output in magentic one

[r-bit-rry]

What feature would you like to be added?

Some of the prompts in magentic one (most noticeable is the ledger update) request a structured output JSON from the model.
Since both Autogen, gpt-4o and even ollama (starting december 2024) support structured output.
I believe there is room to create those classes, basing of BaseModel from pydantic and model_to_json().
I'm raising this here for grabs, but I will start working on it if time allows.

Why is this needed?

Save retry attempts in magentic-one.
Move to a more robust approach in handling responses.
Allow for better tool support by validating arguments for tools.