Support pickling & always manage store prefix

[kylebarron]

See #184 for background

Changes

• Remove separate PrefixStore. Always manage prefix for AWS, GCP, Azure.

TODO:

• Document pickle support. Any middlewares in the future won't be able to be pickled.
• Add dev doc to repo

Closes #125

[maxrjones]

Thanks for your work on this @kylebarron!

How do I get the prefix to be recognized when using S3Store.from_url:

e.g.,

from obstore.store import S3Store
import obstore as obs

bucket = "nasa-veda-scratch"
path = "zarr-obstore-test/max/zarr-v3/test-era5-v3-919"

# Open store with obstore
s3store = S3Store.from_url(f"s3://{bucket}/{path}")
stream = obs.list(s3store, chunk_size=10)
for list_result in stream:
    print(list_result[0])
    break

Currently returns:

{'path': 'icechunk-test/max/met/manifests/4RCPNN1YNY6REGPDAQBG', 'last_modified': datetime.datetime(2025, 1, 27, 21, 8, 48, tzinfo=datetime.timezone.utc), 'size': 214, 'e_tag': '"5622f6e96f657cfc1089e5c5b53f923c"', 'version': None}

[kylebarron]

Hmm this might be a bug in my prefix handling

[maxrjones]

Is it possible to implement __getnewargs_ex__ for LocalStore?

[kylebarron]

@geospatial-jeff benchmarked this (from the 0.4.0-beta.1 tag) as maybe 3% slower than the previous 0.3.0, but that could be partially variation between tests, and would be worth it anyways for these changes.