Fetch and decode one (outer) chunk of a zarr array as raw bytes
Source:R/AnnDataEncoding.R
dot-zarr_fetch_chunk.RdHandles plain chunks and zarr v3 shards. A shard is a single store object
holding a C-ordered grid of inner chunks, each encoded with the inner
codec pipeline, followed (or preceded) by an index of
(offset, nbytes) uint64 pairs, one per inner chunk, optionally with
a crc32c checksum. Missing inner chunks (offset == 2^64 - 1) are filled
with the array's fill value. The result is the decoded, decompressed byte
buffer of the whole outer chunk in C order, exactly as a non-sharded chunk
would decode to.