TIFF/TIF support 
### Feature request

I currently have a dataset (with tiff and json files) where I have to do this:

`wget path_to_data/images.zip && unzip images.zip`

`wget path_to_data/annotations.zip && unzip annotations.zip`
 
 Would it make sense a contribution that supports these type of files? 

### Motivation

instead of using `load_dataset` have to use wget as these files are not supported for annotations with JSON and images with TIFF files. 


Additionally to this, the PIL formatting from datasets does not read correctly the image channels with TIFF format, besides multichannel adaptation might be necessary as well (as my data e.g has more than 3 channels)

### Your contribution

1. Support TIFF images over multi channel format
2. Support JSON annotations
The issue with multichannel TIFF images has already been reported in Pillow (https://github.com/python-pillow/Pillow/issues/1888). We can't do much about it on our side.

Still, to avoid the error, you can bypass the default Pillow decoding and define a custom one as follows:
```python
import tifffile # pip install tifffile

dset = dset.cast_column("image", datasets.Image(decode=False))

def decode_mutlichannel_tiff(batch):
    batch["image"] = [tifffile.imread(image["path"]) for image in batch["image"]]
    return batch

dset.set_transform(decode_mutlichannel_tiff)
```

Regarding the annotations, in which format are they? In the COCO format? I think this is a bit too specific to have a built-in loader for it.