Allow setting of `write_empty_chunks` for `zarr.core.Array` objects

[RKuttruff]

When opening a Zarr group via zarr.hierarchy.open_group() there is currently no way to specify write_empty_chunks=False, this can be problematic when appending to existing zarr groups with sparse data as found in pydata/xarray#8009 / pydata/xarray#8016. A simple solution to this would be setting write_empty_chunks=False for Array objects as they are retrieved from the group. Or, perhaps, allowing the user to specify their preference for write_empty_chunks for Arrays in the group when opening/getting the individual Arrays from the group.