label information get lost after parquet serialization
{'login': 'Tudyx', 'id': 56633664, 'node_id': 'MDQ6VXNlcjU2NjMzNjY0', 'avatar_url': 'https://avatars.githubusercontent.com/u/56633664?v=4', 'gravatar_id': '', 'url': 'https://api.github.com/users/Tudyx', 'html_url': 'https://github.com/Tudyx', 'followers_url': 'https://api.github.com/users/Tudyx/followers', 'following_url': 'https://api.github.com/users/Tudyx/following{/other_user}', 'gists_url': 'https://api.github.com/users/Tudyx/gists{/gist_id}', 'starred_url': 'https://api.github.com/users/Tudyx/starred{/owner}{/repo}', 'subscriptions_url': 'https://api.github.com/users/Tudyx/subscriptions', 'organizations_url': 'https://api.github.com/users/Tudyx/orgs', 'repos_url': 'https://api.github.com/users/Tudyx/repos', 'events_url': 'https://api.github.com/users/Tudyx/events{/privacy}', 'received_events_url': 'https://api.github.com/users/Tudyx/received_events', 'type': 'User', 'site_admin': False}
[{'id': 1935892857, 'node_id': 'MDU6TGFiZWwxOTM1ODkyODU3', 'url': 'https://api.github.com/repos/huggingface/datasets/labels/bug', 'name': 'bug', 'color': 'd73a4a', 'default': True, 'description': "Something isn't working"}]
[]
Hi ! We did a release of `datasets` today that may fix this issue. Can you try updating `datasets` and trying again ?

EDIT: the issue is still there actually

I think we can fix that by storing the Features in the parquet schema metadata, and then reload them when loading the parquet file
## Describe the bug
In *dataset_info.json* file, information about the label get lost after the dataset serialization.

## Steps to reproduce the bug
```python
from datasets import load_dataset

# normal save
dataset = load_dataset('glue', 'sst2', split='train')
dataset.save_to_disk("normal_save")


# save after parquet serialization
dataset.to_parquet("glue-sst2-train.parquet")
dataset = load_dataset("parquet", data_files='glue-sst2-train.parquet')
dataset.save_to_disk("save_after_parquet")
```

## Expected results
I expected to keep label information in *dataset_info.json* file even after parquet serialization

## Actual results
In the normal serialization i got
```json
"label": {
      "num_classes": 2,
      "names": [
        "negative",
        "positive"
      ],
      "names_file": null,
      "id": null,
      "_type": "ClassLabel"
    },
```
And after parquet serialization i got
```json
"label": {
      "dtype": "int64",
      "id": null,
      "_type": "Value"
    },
```

## Environment info
<!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
- `datasets` version: 1.18.0
- Platform: ubuntu 20.04
- Python version: 3.8.10
- PyArrow version: 6.0.1

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