Add Mkqa dataset
the `RemoteDatasetTest ` error pf the CI is fixed on master so it's fine merging since the CI is fixed on master
# MKQA: Multilingual Knowledge Questions & Answers Dataset
Adding the [MKQA](https://github.com/apple/ml-mkqa) dataset as part of the sprint 🎉

There is no official data splits so I added just a `train` split.
 
differently from the original:
- answer:type field is a ClassLabel (I thought it might be possible to train on this as a label for categorizing questions)
- answer:entity field has a default value of empty string '' (since this key is not available for all in original)
- answer:alias has default value of []

- [x] All tests passed
- [x] Added dummy data
- [x] Added data card (as much as I could)
