Add SEDE dataset
Thanks @albertvillanova for your great suggestions! I just pushed a new commit with the necessary fixes. For some reason, the test `test_metric_common` failed for `meteor` metric, which doesn't have any connection to this PR, so I'm trying to rebase and see if it helps. Hi @Hazoom,

You were right: the non-passing test had nothing to do with this PR.

Unfortunately, you did a git rebase (instead of a git merge), which is not recommended once you have already opened a pull request because you mess up your pull request history. You can see that your pull request now contains:
- your commits repeated two times
- and commits which are not yours from the master branch

If you would like to clean your pull request, please make:
```
git reset --hard 587b93a
git fetch upstream master
git merge upstream/master
git push --force origin sede
``` > Hi @Hazoom,
> 
> You were right: the non-passing test had nothing to do with this PR.
> 
> Unfortunately, you did a git rebase (instead of a git merge), which is not recommended once you have already opened a pull request because you mess up your pull request history. You can see that your pull request now contains:
> 
> * your commits repeated two times
> * and commits which are not yours from the master branch
> 
> If you would like to clean your pull request, please make:
> 
> ```
> git reset --hard 587b93a
> git fetch upstream master
> git merge upstream/master
> git push --force origin sede
> ```

Thanks @albertvillanova  > Nice! Just one final request before approving your pull request:
> 
> As you have updated the "QuerySetId" field data type, the size of the dataset is smaller now. You should regenerate the metadata. Please run:
> 
> ```
> rm datasets/sede/dataset_infos.json
> datasets-cli test datasets/sede --save_infos --all_configs
> ```

@albertvillanova Good catch, just fixed it.
This PR adds the SEDE dataset for the task of realistic Text-to-SQL, following the instructions of how to add a database and a dataset card.

Please see our paper for more details: https://arxiv.org/abs/2106.05006