[FEATURE] SelfInstruct predefined structured output

[plaguss]

Description

As part of issue #832, we started adding default structured outputs for tasks that could benefit from it. SelfInstruct is a good candidate.

PR #868 can be used as a guide on what to update.

[ignacioct]

Hi @plaguss ! Do you think this issue is a good (re)starting point?

[plaguss]

Hey @ignacioct! Sure, let me know if you need help, there should be examples in other steps (like UtraFeedback) to see how this can be implemented.

[ignacioct]

@plaguss I started to play a bit with distilabel yesterday, and I tried to run it locally using Ollama models, but was not succesful. As I don't have access to any API like OpenAI's, do you know what's the best strategy for running LLMs locally with distilabel? Maybe vLLMs? We can discuss it via Discord if you wanna, I just couldn't find you there earlier :)