Lack of zstd compression support

[Czaki]

It looks like CZI file format was updated to support compressing data using zstd that is no supported by this package yet.

based on my investigation they added two modes. 5: zstd0 (plain zstd, but do not have such file to test) https://github.com/ZEISS/libczi/blob/4a60e22200cbf0c8ff2a59f69a81ef1b2b89bf4f/Src/libCZI/decoder_zstd.cpp#L39

And mode 6 named zstd1

https://github.com/ZEISS/libczi/blob/4a60e22200cbf0c8ff2a59f69a81ef1b2b89bf4f/Src/libCZI/decoder_zstd.cpp#L39

So it seems like to support mode 5 it will be enough to add

DECOMPRESS[5] = imagecodecs.zstd_decode

to this dict

https://github.com/cgohlke/czifile/blob/a70265fd430983875bf4c31955f2ad57f2592747/czifile/czifile.py#L1227-L1231

Mode 6 requires to add parsing header and decoding that may be done with such a code:

class ZSTD1Header(typing.NamedTuple):
    """
    ZSTD1 header structure
    based on:
    https://github.com/ZEISS/libczi/blob/4a60e22200cbf0c8ff2a59f69a81ef1b2b89bf4f/Src/libCZI/decoder_zstd.cpp#L19
    """

    header_size: int
    hiLoByteUnpackPreprocessing:bool

def parse_zstd1_header(data, size):
    """
    Parse ZSTD header

    https://github.com/ZEISS/libczi/blob/4a60e22200cbf0c8ff2a59f69a81ef1b2b89bf4f/Src/libCZI/decoder_zstd.cpp#L84
    """
    if size < 1:
        return ZSTD1Header(0, False)

    if data[0] == 1:
        return ZSTD1Header(1, False)

    if data[0] == 3 and size < 3:
        return ZSTD1Header(0, False)

    if data[1] == 1:
        return ZSTD1Header(3, bool(data[2] & 1))

    return ZSTD1Header(0, False)

def decode_zstd1(data):
    """
    Decode ZSTD1 data
    """
    header = parse_zstd1_header(data, len(data))
    return imagecodecs.zstd_decode(data[header.header_size:])

(this code does not support hilo byte unpacking, I do not dig it yet).

Hovewer provide own decode function is not enough, as zstd_decode return bytes, not array.

So it require update also this line: https://github.com/cgohlke/czifile/blob/a70265fd430983875bf4c31955f2ad57f2592747/czifile/czifile.py#L660

to

if de.compression in {2, 5, 6}:

The current example file that I had is 500mb so require an alternative way to share. I try to obtain a smaller one.

Did you prefer to do this on your site or PR?