Support for N5 drag and drop

[martlj]

Hi, I gather that ome-zarr is able to handle N5 files (via https://zarr.readthedocs.io/en/stable/api/n5.html). Some of our workflows are currently using a mix of N5 and ome-zarr (e.g. from MoBIE projects in Fiji), with a view to using only ome-zarr in the future. If drag-and-drop of N5 into the napari plugin would be possible it'd help with not having to write custom scripts or convert large files. I don't envisage needing to write N5, only read.

Cheers,
Martin