Add context to guide the generate sentence pair task if informed

[plaguss]

Description

This PR adds a new optional context to the GenerateSentencePair task to help guiding the prompts:

from distilabel.steps import GenerateSentencePair

task = GenerateSentencePair(
    llm=llm,
    action="query",
    triplet=True,
    context="The generated sentence has to be related with Argilla, a data annotation tool for AI engineers and domain experts.",
)

Context

The original prompt, given a "hard" instruction (or possibly quite meaningless without context) could generate unexpected queries, for reference:

With context, it can generate more meaningful queries:

[codspeed-hq]

CodSpeed Performance Report

Merging #706 will not alter performance

_{Comparing generate-sentence-pair-context (3b7c221) with develop (34ac772)}

Summary

✅ 1 untouched benchmarks