Crop does not work with multiscale images

[tdmorello]

crop_region fails to crop multiscale (like pyramid format) images. I think it will be import to support pyramid ome-tiff's and NGFF moving forward.

Some thoughts:
If the crop is large, it should copy or regenerate pyramids for the resulting image
If the crop is small, it might make sense to only keep the highest scale image

[VolkerH]

Just another +1 to this !

[pr4deepr]

+1 as well

One approach is to:

• Check if layer data type is multiscale: napari.layers._multiscale_data.MultiScaleData
• If so, get the length of the layer, which will show how many scales there are.

Let the user decide which scale to crop (possibly easier).
OR
iterate through all scales, crop all of them at different scales and merge.