Improvements to OMERarr

[Artur-man]

A summary of tasks to improve compliance of OMERarr with OME-NGFF/ZARR specifications:

• Use OME JSON Schema for validation #1
• OME-ZARR metadata #2
• NGFF Coordinate transformation #3
• GHA for OME-ZARR conformance #4
• Read/write support for Zarr v2/v3 #5
• Example datasets for tutorials/tests #7

[Artur-man]

Most of these utilities now are in https://github.com/Huber-group-EMBL/rome, and moved over there.