Allow validating local datasets

[dstansby]

I just tried validating a local file, and the tool didn't seem to work - the link I used was https://ome.github.io/ome-ngff-validator/?source=file:///Users/dstansby/notebooks/ct-scans/david_ct_scan.zarr, and the directory definitely exists. The error message is:

Error Loading file:///Users/dstansby/notebooks/ct-scans/david_ct_scan.zarr/.zattrs: TypeError: NetworkError when attempting to fetch resource.

[will-moore]

The easiest solution is to use ome-zarr-py:

$ ome_zarr view path/to/ct-scans/david_ct_scan.zarr

That will serve the zarr locally and automatically open it in ome-ngff-validator.

See https://ome-zarr.readthedocs.io/en/stable/cli.html#view
It actually looks best if you don't add the trailing slash as above (not like in the docs)