fixing NDArray save method to use its own compression parameters

[evgmik]

The 'NDArray.save' method does not path 'cparams' to the parent class 'copy' consequently array is reprocessed with the default 'cparams'.

To observe the bug run the script below.

================================================================= import os
import blosc2
import numpy as np

a = np.arange(10_000_000)
a = a * a

cparams = blosc2.CParams(
codec=blosc2.Codec.ZSTD,
clevel=9,
filters=[blosc2.Filter.BITSHUFFLE],
)

ba = blosc2.asarray(a, cparams=cparams)
print(f"Blosc2 memory: size {ba.cbytes}\t cratio: {ba.cratio}")

outdir = "cache/"
prefix = "save"
fname = outdir + prefix + ".b2nd"
ba.save(fname, mode="w")
fsize = os.path.getsize(fname)
print(f"Blosc2 array save:\t saved file size = {fsize}\t cratio: {a.nbytes/fsize}")

=================================================================

You should see

Blosc2 memory: size 4370284      cratio: 18.74477722729232
Blosc2 array save:       saved file size = 12370369      cratio: 6.467066584675041

ba.cbytes ---> 4370284
ba.cratio ---> 18.3

I.e. the array in memory has 'cbytes=4370284',
however the saved file has 12370369 bytes, which gives 'cratio' of about 6.5. Also if the array is loaded back from the file, it is easy to see that 'cparams' are different from the original array and changed to the default one.

After the patch, the memory 'cbytes' are closely matching the saved file size as well as 'cparams'

Blosc2 memory: size 4370284      cratio: 18.74477722729232
Blosc2 array save:       saved file size = 4370051       cratio: 18.30642251085856

[FrancescAlted]

LGTM. Thanks @evgmik !