Zarr V2 vs V3

[TomNicholas]

What needs to be done here?

[TomNicholas]

Ideally we would be able to import Zarr objects from zarr-python that help us navigate the differences between v2 and v3

[TomNicholas]

So Zarr v3 was released last week (it's on PyPI, and can be installed by specifying --pre with pip install). This means we can start the process of refactoring virtualizarr to use the v3 zarr-python library for some internal abstractions.

In particular I want to replace the virtualizarr.zarr.ZArray class. I haven't really looked at the v3 code much at all yet, but I'm hoping there is some drop-in for the ZArray class that can smoothly handle the difference between Zarr v2 and v3 arrays for us. (And if there's not we should be making suggestions upstream.)