Serve Zarr Image files directly

[will-moore]

If an OMERO Image is actually an OME-Zarr, then we should serve the actual zarr files, instead of generating them.

For each URL, we'll need to check if the image is a Zarr, if so then check for the existence of the requested file in the Fileset.

E.g. /zarr/image/ID.zarr/.zattrs, /zarr/image/ID.zarr/0/.zarray, /zarr/image/ID.zarr/0/0/0/0/0

However, in the case that this is an Image in a Plate then we need to know which Well it is in and build the path accordingly.
E.g. if image 123 is in Well A1, field 2 then

URL: /zarr/image/123.zarr/.zattrs needs to serve fileset-prefix/plate.zarr/A/1/2/.zattrs etc.

NB: Bio-Formats can also tell us which files form a Fileset are related to a particular image, but might not need this?
https://github.com/search?q=org%3Aome%20binaryFilesThisSeries&type=code