expanduser in save_to_disk
### Describe the bug

save_to_disk() does not expand `~`

1. `dataset = load_datasets("any dataset")`
2. `dataset.save_to_disk("~/data")`
3. a folder named "~" created in current folder
4. FileNotFoundError is raised, because the expanded path does not exist (`/home/<user>/data`)

related issue https://github.com/huggingface/transformers/issues/10628

### Steps to reproduce the bug

As described above.

### Expected behavior

expanduser correctly

### Environment info

- datasets 2.10.1
- python 3.10
`save_to_disk` should indeed expand `~`. Marking it as a "good first issue". #self-assign

File path to code: 

https://github.com/huggingface/datasets/blob/2.13.0/src/datasets/arrow_dataset.py#L1364

@RmZeta2718 I created a pull request for this issue.  Hello, 
It says `save_to_disk` is deprecated in 2.8.0, so the alternative to this will be `storage_options`? 

https://huggingface.co/docs/datasets/package_reference/main_classes#datasets.Dataset.save_to_disk @ashikshafi08 I think you misunderstood the warning. The method `save_to_disk` is not deprecated only the optional parameter `fs`.
Also @benjaminbrown038 as I cannot find your PR I would like to work on this if you don't mind.