Dataset string representation enhancement
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_6016). All of your documentation changes will be reflected on that endpoint. It we could have something similar to Polars, that would be great.

This is what Polars outputs: 
* `__repr__`/`__str__` :
```
shape: (67_349, 3)
┌───────┬───────────────────────────────────┬───────┐
│ idx   ┆ sentence                          ┆ label │
│ ---   ┆ ---                               ┆ ---   │
│ i32   ┆ str                               ┆ i64   │
╞═══════╪═══════════════════════════════════╪═══════╡
│ 0     ┆ hide new secretions from the par… ┆ 0     │
│ 1     ┆ contains no wit , only labored g… ┆ 0     │
│ 2     ┆ that loves its characters and co… ┆ 1     │
│ 3     ┆ remains utterly satisfied to rem… ┆ 0     │
│ …     ┆ …                                 ┆ …     │
│ 67345 ┆ anguish , anger and frustration   ┆ 0     │
│ 67346 ┆ at achieving the modest , crowd-… ┆ 1     │
│ 67347 ┆ a patient viewer                  ┆ 1     │
│ 67348 ┆ this new jangle of noise , mayhe… ┆ 0     │
└───────┴───────────────────────────────────┴───────┘
```

* `_repr_html_`:
<img width="251" alt="Screenshot 2023-07-12 at 18 25 58" src="https://github.com/huggingface/datasets/assets/47462742/5d04519d-f302-4411-9fbc-7445bdf53b23">


my attempt at #6010  
not sure if this is the right way to go about it, I will wait for your feedback 