Implement support for structured and struct zarr-extension defined dtypes

[BrianMichell]

Updates for consistency with the zarr-extension for structured types.

Implements legacy read-only for structured type and support for new struct definition.

TODO:

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/user-guide/*.md
• Changes documented as a new file in changes/
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)

[d-v-b]

this looks great, thanks for this. Instead of modifying the existing structured data type, can we make struct as a subclass of that data type, and register it? That means people who need the legacy dtype can still use it (by overriding the registry)

[BrianMichell]

this looks great, thanks for this. Instead of modifying the existing structured data type, can we make struct as a subclass of that data type, and register it? That means people who need the legacy dtype can still use it (by overriding the registry)

Should be good to go now!

[BrianMichell]

@d-v-b Is there anything I can do to move this PR forward?

[codecov]

Codecov Report

❌ Patch coverage is 92.53731% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.11%. Comparing base (be0a7b8) to head (dd6b846).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/zarr/codecs/bytes.py	60.00%	4 Missing ⚠️
src/zarr/core/dtype/npy/structured.py	98.18%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3781      +/-   ##
==========================================
- Coverage   93.19%   93.11%   -0.09%     
==========================================
  Files          85       85              
  Lines       11302    11365      +63     
==========================================
+ Hits        10533    10582      +49     
- Misses        769      783      +14     

Files with missing lines	Coverage Δ
src/zarr/core/array.py	97.71% <100.00%> (ø)
src/zarr/core/dtype/__init__.py	100.00% <100.00%> (ø)
src/zarr/dtype.py	100.00% <ø> (ø)
src/zarr/core/dtype/npy/structured.py	92.56% <98.18%> (-6.37%)	⬇️
src/zarr/codecs/bytes.py	92.75% <60.00%> (-5.58%)	⬇️

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[d-v-b]

@d-v-b Is there anything I can do to move this PR forward?

hi @BrianMichell thanks for the ping, I will get a review in soon. since numpy is handling the actual data type, I think we will ask much less of you than the tensorstore devs :)

[d-v-b]

I think this is good to go in @BrianMichell, thanks for your patience here.

[BrianMichell]

Thanks, @d-v-b ! Would it be possible to get this merged in before the next release? It's fine if not, just need to know whether it's worth delaying one of my releases for this change.

[d-v-b]

Thanks, @d-v-b ! Would it be possible to get this merged in before the next release? It's fine if not, just need to know whether it's worth delaying one of my releases for this change.

it's going in now!