Add easy ways to get data arrays

[dstansby]

This is insipred by ome/napari-ome-zarr#123 (comment). Something like a method on Image classes that looks like:

def get_zarr_array(..., backend: Literal["zarr-python", "tensorstore"]):
    ...

@jo-mueller don't know if you have any other thoughts or ideas?

[jo-mueller]

Hm...my guess as a "new" user would probably always be to query Image objects for either Image.data or Image.get_data(...). In any case, why is the Image exclusive to the 06 metadata? For easy access I would expect that (aside from zarr v2/v3 topic) only the metadata needs to be versioned?