(feat): allow writing from cupy inside dask arrays

[ilan-gold]

• Closes GPU writing #1549 (so part of Dask gpu #1480)
• Tests added
• Release note added (or unnecessary)

[codecov]

Codecov Report

Attention: Patch coverage is 93.33333% with 6 lines in your changes missing coverage. Please review.

Project coverage is 86.56%. Comparing base (4c70aa8) to head (26a2c21).
Report is 67 commits behind head on main.

Files with missing lines	Patch %	Lines
src/anndata/tests/helpers.py	94.11%	4 Missing ⚠️
src/anndata/compat/__init__.py	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1550      +/-   ##
==========================================
+ Coverage   84.43%   86.56%   +2.13%     
==========================================
  Files          36       36              
  Lines        5782     5851      +69     
==========================================
+ Hits         4882     5065     +183     
+ Misses        900      786     -114     

Files with missing lines	Coverage Δ
src/anndata/_io/specs/methods.py	88.40% <100.00%> (+0.42%)	⬆️
src/anndata/_io/specs/registry.py	96.31% <100.00%> (+0.04%)	⬆️
src/anndata/compat/__init__.py	84.38% <66.66%> (+0.83%)	⬆️
src/anndata/tests/helpers.py	94.06% <94.11%> (+7.83%)	⬆️

... and 4 files with indirect coverage changes

[ilan-gold]

I'm not sure what's up with codecov. I believe those lines are being hit and when I look at the github GPU job, it says we have reached an upload limit:
https://github.com/scverse/anndata/actions/runs/9763035863/job/26947927670?pr=1550

[ivirshup]

lgtm (but still needs a release note), maybe @Intron7 could take a quick look too on the cupy stuff.

Have you looked into fixing the codecov issue?

[ilan-gold]

Have you looked into fixing the codecov issue?

https://scverse.zulipchat.com/#narrow/stream/316218-repo-management/topic/codecov.20limit/near/448627892

[Intron7]

LGTM