Breaking API change in datasets.list_datasets caused by change in HfApi.list_datasets
### Describe the bug

Hi all,

after an update of the `datasets` library, we observer crashes in our code. We relied on `datasets.list_datasets` returning a `list`. Now, after the API of the HfApi.list_datasets was changed and it returns a `list` instead of an `Iterable`, the `datasets.list_datasets` now sometimes returns a `list` and somesimes an `Iterable`. 

It would be helpful to indicate that by the return type of the `datasets.list_datasets` function.

Thanks,
Martin 

### Steps to reproduce the bug

Here, the code crashed after we updated the `datasets` library:

```python
# list_datasets no longer returns a list, which leads to an error when one tries to slice it
for datasets.list_datasets(with_details=True)[:limit]:
    ...
```

### Expected behavior

It would be helpful to indicate that by the return type of the `datasets.list_datasets` function.

### Environment info

Ubuntu 22.04
datasets 2.12.0