Add new serialization strategy

[plaguss]

Description

This PR adds a new module distilabel.utils.serialization to allow custom serialization of the tasks (to be extended to the different distilabel components in the future). When we save/load from disk, we will have a task-distilabel.json instead of task.pkl.

• This definition will replace the current one based in pickle, making it safer to move the files around.
• Currently the definition is completely custom, but we could use the pydantic one if we see fit.

Sample task from UltraFeedbackTask:

{
  "system_prompt": "You are an expert prompt writer, writing the best and most diverse prompts for a variety of tasks. You are given a task description and a set of instructions for how to write the prompts for an specific AI application.",
  "principles": {
    "harmlessness": [
      "The assistant should not provide answers that could cause physical, psychological, or social harm to any group of people; damage to or loss of equipment or property; damage to the environment; or harm to institutions or resources necessary to human wellbeing. Feel free to refuse to answer questions that could cause the above harm.",
     "..."
    ],
    "helpfulness": [
      "The assistant should provide users with accurate, relevant, and up-to-date information, ensuring that the content is positive, interesting, engaging, educational, and helpful.",
      "As an AI assistan..."
  "principles_distribution": null,
  "application_description": "AI assistant",
  "num_instructions": 5,
  "criteria_for_query_generation": "Incorporate a diverse range of verbs, avoiding repetition.\nEnsure queries are compatible with AI model's text generation functions and are limited to 1-2 sentences.\nDesign queries to be self-contained and standalone.\nBlend interrogative (e.g., \"What is the significance of x?\") and imperative (e.g., \"Detail the process of x.\") styles.",
  "__jinja2_template__": "...",
  "__type_info__": {
    "module": "distilabel.tasks.text_generation.self_instruct",
    "name": "SelfInstructTask"
}

Closes #261.

[davidberenstein1957]

shouldn't we be able to replace load_task_from_disk too?

[plaguss]

what do you mean exactly?

[davidberenstein1957]

We call self.task.save but though we might also add load_task_from_disk in that load_from_diskfuncton but now see it is inheriting from Dataset so that does not make sense

[plaguss]

Yes those two are different, one for the dataset which we don't really deal with it ourselves, and the task which is saved as a json file.

[plaguss]

Still need to review some private variables from the dump