More tests for compatibility with zarr-python implementation

[keller-mark]

• [x] We should test that stores/arrays/groups written by zarr-python are read-able by pizzarr.
• [x] We should test that stores/arrays/groups written by pizzarr are read-able by zarr-python.

[dblodgett-usgs]

I just did:

library(pizzarr)

dir <- "./tests/testthat/test_data/write_test.zarr"

z <- DirectoryStore$new(dir)

a <- volcano

za <- zarr_create(dim(volcano), store = z, overwrite = TRUE)

za$set_item("...", a)

With that file, I can do:

import zarr

zarr.open_array("write_test.zarr")

# <zarr.core.Array (87, 61) float64>

This test identified the bug with unboxing json that's fixed in #85

What other aspects of pizzarr output should we be testing you think?

[dblodgett-usgs]

Think we can call this done @keller-mark ?

[keller-mark]

Yes that sounds good