Add support for UnsignedLongType in volumes

[kephale]

I ran into this Unknown volume type class net.imglib2.type.numeric.integer.UnsignedLongType when testing this s3 bucket from mobie https://s3.embl.de/i2k-2020/platy-raw.ome.zarr

I guess we're going to need to support this pixel type as well.