Support features in metadata configs
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7182). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update. The CI issue is unrelated:
- #7183
Support features in metadata configs, like:
```
configs:
  - config_name: default
    features:
      - name: id
        dtype: int64
      - name:  name
        dtype: string
      - name: score
        dtype: float64
```

This will allow to avoid inference of data types.

Currently, we allow passing this information in the `dataset_info` (instead of `configs`) field, but this is not intuitive and it is not properly documented.

TODO:
- [ ] Document usage