Support faster processing using pandas or polars functions in `IterableDataset.map()`
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/datasets/pr_7370). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update. merging this and will make some docs and communications around using polars for optimizing data processing :)
Following the polars integration :)

Allow super fast processing using pandas or polars functions in `IterableDataset.map()` by adding support to pandas and polars formatting in `IterableDataset`

```python
import polars as pl
from datasets import Dataset

ds = Dataset.from_dict({"i": range(10)}).to_iterable_dataset()
ds = ds.with_format("polars")
ds = ds.map(lambda df: df.with_columns(pl.col("i").add(1).alias("i+1")), batched=True)
ds = ds.with_format(None)
print(next(iter(ds)))
# {'i': 0, 'i+1': 1}
```

It leverages arrow's zero-copy features from/to pandas and polars.

related to https://github.com/huggingface/datasets/issues/3444 #6762 