Add labels support for import

[will-moore]

This reverts commit 9fea245.

To test:

• with a bioformats2raw image (2 out of 3 images have labels):

$ omero zarr import https://uk1s3.embassy.ebi.ac.uk/idr/zarr/v0.4/idr0079A/idr0079_images.zarr --labels --target 23619

• regular image

$ omero zarr import https://uk1s3.embassy.ebi.ac.uk/idr/zarr/v0.4/idr0062A/6001240.zarr --labels --target 23619

This PR converts labels into masks. This is not a similar "import" than the one we have for images
The current tooling in OMERO will need to be reviewed in order to support a true "import" of labels
i.e. only reference to it

[snoopycrimecop]

Conflicting PR. Removed from build OMERO-plugins-push#543. See the console output for more details.
Possible conflicts:

• PR Use zarr v3 and updated ome-zarr-py #172 will-moore 'Use zarr v3 and updated ome-zarr-py'
  • src/omero_zarr/zarr_import.py

--conflicts Conflict resolved in build OMERO-plugins-push#576. See the console output for more details.