[FEATURE] Allow Steps to produce artifacts

[gabrielmbmb]

Is your feature request related to a problem? Please describe.
Some Steps might produce some artifacts (faiss index for example) that could be reused after the pipeline has finished its execution. distilabel currently doesn't allow to save any artifact, or does not provide a clear way, for an Step to save artifacts.

Describe the solution you'd like
Steps can produce and save artifacts that can be later upload along the produced dataset to the Hub. To do so, Step offers a method get_artifact_directory that can be used within the step to a get directory (from the cache of the pipeline) that can be used by the step to store produced artifacts.