Add semantic dimension identifier to concat API

[flying-sheep]

• Closes Concat API lacks semantic dimension identifier #1245
• Tests added
• Release note added (or unnecessary)

Follows the consensus axis/axis_name

[codecov]

Codecov Report

Attention: Patch coverage is 97.36842% with 1 line in your changes missing coverage. Please review.

Project coverage is 84.34%. Comparing base (1bff5fb) to head (f346188).
Report is 59 commits behind head on main.

Files with missing lines	Patch %	Lines
src/anndata/experimental/merge.py	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1244      +/-   ##
==========================================
+ Coverage   84.27%   84.34%   +0.06%     
==========================================
  Files          35       35              
  Lines        5693     5685       -8     
==========================================
- Hits         4798     4795       -3     
+ Misses        895      890       -5     

Files with missing lines	Coverage Δ
src/anndata/_core/aligned_mapping.py	91.96% <100.00%> (ø)
src/anndata/_core/anndata.py	84.96% <100.00%> (ø)
src/anndata/_core/merge.py	84.17% <100.00%> (+0.64%)	⬆️
src/anndata/utils.py	84.21% <100.00%> (ø)
src/anndata/experimental/merge.py	91.37% <93.75%> (ø)

[ivirshup]

I commented on the original issue, but basically would like to discuss this.

To me, you are proposing that we do a broad API change of introducing a keyword argument dim which is analogous to axis, but refers to the axes as "obs", "var" instead of 0, 1. I would like to at least discuss the implications of this, especially considering that we allow names to be set dynamically on the dimensions. Let's do this on the issue.

I also would not consider this a bug fix as it introduces a new element to the API.

[ivirshup]

A couple points.

It would also be good to address the missing coverage on the added code.

• axis_size may be able to just get deleted
• dim_len could probably get deleted (was it used somewhere?), or it should get a deprecation test

[flying-sheep]

all done, including the axis_size and dim_len parts

[ivirshup]

@flying-sheep could you merge main on this one?

[flying-sheep]

done!

addressed