[Summary] Add popular NLG faithfulness evaluation datasets

[gsarti]

🚀 Feature Request

In order to facilitate the evaluation of different interpretability techniques, I propose to identify a set of commonly used datasets from the literature, create 🤗 Datasets loading scripts to have them in a shared format, and host them on the Inseq organization in the Hugging Face hub.

This would provide a shared interface for:

• Faithfulness metrics applied at a dataset level.
• Future support of instance attribution methods.

The following table summarizes some of the datasets used in the literature:

Name	Task	Data source	Paper	Description
SCAT	Translation	neulab/contextual-mt	Yin et al. '21	Contextual coreference in translation, with disambiguating context highlights from translators
Lambada + Rationales	Language Modeling	keyonvafa/sequential-rationales	Vafa et al. '21	Next word prediction with human-annotated previous relevant context
Europarl Gold Alignments	Translation	TBD	TBD	Gold alignments for various language pairs in the Europarl corpus

The ExNLP Datasets website summarizes various sources available for NLP explainability, verify what is relevant to generation.