JSON mode support

[you-n-g]

🌟 Feature Description

Currently, the RD-Agent workflow relies heavily on JSON mode to simplify implementation.

However, many LLMs do not natively support the JSON model.

RD-Agent should offer a fallback solution, even though it might result in a higher error rate.

A very naive proposal

• The json mode should be transparent and make the interface consistant with current design.
• It may internelly add some prompts like "you should return only in json format as described in previous content."
• Do necessary post processing like strip ```` fence

[you-n-g]

#419 is related

[frinkleko]

There are also some related tools for json repair in the output of LLM, such as this repo.

[NAMEKDSUN]

Whether this package is useful for the project？https://github.com/dottxt-ai/outlines