Issue: Addition of google drive links to dl_manager

Hello there, I followed the template to create a download script of my own, which works fine for me, although I had to shun the dl_manager because it was downloading nothing from the drive links and instead use gdown.

This is the script for me:

```python
class EmoConfig(nlp.BuilderConfig):
    """BuilderConfig for SQUAD."""

    def __init__(self, **kwargs):
        """BuilderConfig for EmoContext.
    Args:
      **kwargs: keyword arguments forwarded to super.
    """
        super(EmoConfig, self).__init__(**kwargs)

_TEST_URL = "https://drive.google.com/file/d/1Hn5ytHSSoGOC4sjm3wYy0Dh0oY_oXBbb/view?usp=sharing"
_TRAIN_URL = "https://drive.google.com/file/d/12Uz59TYg_NtxOy7SXraYeXPMRT7oaO7X/view?usp=sharing"

class EmoDataset(nlp.GeneratorBasedBuilder):
    """ SemEval-2019 Task 3: EmoContext Contextual Emotion Detection in Text. Version 1.0.0 """

    VERSION = nlp.Version("1.0.0")
    force = False

    def _info(self):
        return nlp.DatasetInfo(
            description=_DESCRIPTION,
            features=nlp.Features(
                {
                    "text": nlp.Value("string"),
                    "label": nlp.features.ClassLabel(names=["others", "happy", "sad", "angry"]),
                }
            ),
            supervised_keys=None,
            homepage="https://www.aclweb.org/anthology/S19-2005/",
            citation=_CITATION,
        )
    
    def _get_drive_url(self, url):
        base_url = 'https://drive.google.com/uc?id='
        split_url = url.split('/')
        return base_url + split_url[5]
    
    def _split_generators(self, dl_manager):
        """Returns SplitGenerators."""
        if(not os.path.exists("emo-train.json") or self.force):
            gdown.download(self._get_drive_url(_TRAIN_URL), "emo-train.json", quiet = True)
        if(not os.path.exists("emo-test.json") or self.force):
            gdown.download(self._get_drive_url(_TEST_URL), "emo-test.json", quiet = True)
        return [
            nlp.SplitGenerator(
                name=nlp.Split.TRAIN,
                gen_kwargs={
                    "filepath": "emo-train.json",
                    "split": "train",
                },
            ),
            nlp.SplitGenerator(
                name=nlp.Split.TEST,
                gen_kwargs={"filepath": "emo-test.json", "split": "test"},
            ),
        ]

    def _generate_examples(self, filepath, split):
        """ Yields examples. """
        with open(filepath, 'rb') as f:
            data = json.load(f)
            for id_, text, label in zip(data["text"].keys(), data["text"].values(), data["Label"].values()):
                yield id_, {
                    "text": text,
                    "label": label,
                }
```

Can someone help me in adding gdrive links to be used with default dl_manager or adding gdown as another dl_manager, because I'd like to add this dataset to nlp's official database.

Comments:
I think the problem is the way you wrote your urls. Try the following structure to see `https://drive.google.com/uc?export=download&id=your_file_id` . 

@lhoestq  

Oh sorry, I think `_get_drive_url` is doing that. 

Have you tried to use `dl_manager.download_and_extract(_get_drive_url(_TRAIN_URL)`? it should work with google drive links.


Yes it worked, thank you!