Add  KorQuAD v2 Dataset
looks like this PR also includes the changes for the V1
Could you only include the files of the V2 ? hmm I have made the dummy data lighter retested on local and it passed not sure why it fails here? merging since the CI is fixed on master
# The Korean Question Answering Dataset v2
Adding the [KorQuAD](https://korquad.github.io/) v2 dataset as part of the sprint 🎉 
This dataset is very similar to SQuAD and is an extension of [squad_kor_v1](https://github.com/huggingface/datasets/pull/1178) which is why I added it as `squad_kor_v2`. 

- Crowd generated questions and answer (1-answer per question) for Wikipedia articles. Differently from V1 it includes the html structure and markup, which makes it a different enough dataset. (doesn't share ids between v1 and v2 either)

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

Edit: 🤦 looks like squad_kor_v1 commit sneaked in here too