Add CodeXGLUE-text-to-text benchmark for documentation translation

[loubnabnl]

Add this benchmark for documentation translation to the evaluation harness: https://huggingface.co/datasets/code_x_glue_tt_text_to_text

• few-shot setting (see CoNaLa and Spider tasks for examples)
• fine-tning

[infinitylogesh]

Hi, I am interested in taking this up !

[loubnabnl]

Great, let us know if you need any help!