IterableDataset missing column_names, differs from Dataset interface
### Describe the bug

The documentation on [Stream](https://huggingface.co/docs/datasets/v1.18.2/stream.html) seems to imply that IterableDataset behaves just like a Dataset. However, examples like
```
dataset.map(augment_data, batched=True, remove_columns=dataset.column_names, ...)
```
will not work because `.column_names` does not exist on IterableDataset. I cannot find any clear explanation on why this is not available, is it an oversight? We do have `iterable_ds.features` available.

### Steps to reproduce the bug

See above

### Expected behavior

Dataset and IterableDataset would be expected to have the same interface, with any differences noted in the documentation.

### Environment info

n/a