Provide a tool to LLM to split response into multiple small nodes

[LemonNekoGH]

Thanks to @shinohara-rin

[shinohara-rin]

Originally, I thought that allowing the LLM to create multiple tree nodes would be fun and lead to interesting use cases. However, that's gonna require some system prompts, which may conflict with the chat template system.

I'll experiment with this a bit on my end and see if this feature actually makes any sense.