remove language restrictions in tydiqa + add arabic prompts (#763)

* remove language restrictions

* add arabic dataset to primary_task

* Accelerate `get_infos` by caching the `DataseInfoDict`s (#778)

* accelerate `get_infos` by caching the `DataseInfoDict`s

* quality

* consistency

* add arabic prompts

* cleaning

* Consistency in prompt naming.

* cleaning

* fix `filter_english_datasets` since `languages` became `language` in dataset metadatas

* fix empty documents - multi_news (#793)

* fix empty documents - multi_news

* fix test - unrecognized variable

* Language tags (#771)

* Added languages widget to UI.

* Style fixes.

* Added English tag to existing datasets.

* Add languages to viewer mode.

* Update language codes.

* Update CONTRIBUTING.md.

* Update screenshot.

* Add "Prompt" to UI to clarify languages tag usage.

* update

* update prompts

* Remove duplicates lines

* update

* regenerate prompts

* cleaning

* lang tag missing

Co-authored-by: Victor SANH <[email protected]>
Co-authored-by: Stephen Bach <[email protected]>

Author: 3 people