Add ability to upload (OME-)Zarr volume annotations

[dstansby]

Detailed Description

I'm trying to upload a volume annotation that is in a zarr array: I have tried uploading both the 'raw' zarr array, and an OME-Zarr dataset (
494.08um_hippocampus1_label.ome.zarr.zip), and when I try to drag and drop zip files of these into the webknossos annotations tab I get an error that says "NML upload failed". The docs say

To import a volume annotation, ensure it is in the correct format (WKW or Zarr)

So I expected this to work. But maybe it is not implemented, and this is a feature request instead of a bug?

Context

• Specific to long-running jobs (set jobsEnabled=true in application.conf)
• Specific to webknossos.org (set isDemoInstance=true in application.conf)

[normanrz]

We don't really support uploading segmentation annotations at this point. It possible to upload segmentation layers as part of datasets and then edit the segmentation via the annotation tools, though.