transformers pytorch tf jax rust safetensors mbart text2text-generation mbart-50 multilingual ar cs de en es et fi fr gu hi it ja kk ko lt lv my ne nl ro ru si tr vi zh af az bn fa he hr id ka km mk ml mn mr pl ps pt sv sw ta te th tl uk ur xh gl sl arxiv:2008.00401 autotrain_compatible endpoints_compatible region:us