Fixes for MuData 0.3 release

[gtca]

• [x] Fix nested MuData dimensions in __repr__()
• [x] Fix .uns contents for views (#52)
• [x] Use mod-order attribute in read_zarr() (#48)
• [x] Avoid sorting .var_names in the global index when modalities are added and .var_names are intersecting (#46)
• [x] Coerce nullable boolean arrays to bool when there are no null values (https://github.com/scverse/muon/issues/111)

[codecov-commenter]

Codecov Report

Merging #53 (7fe6259) into mudata-0.3 (29b5a11) will increase coverage by 1.06%. Report is 5 commits behind head on mudata-0.3. The diff coverage is 76.33%.

Additional details and impacted files

@@              Coverage Diff               @@
##           mudata-0.3      #53      +/-   ##
==============================================
+ Coverage       69.12%   70.19%   +1.06%     
==============================================
  Files              14       17       +3     
  Lines            1671     1892     +221     
==============================================
+ Hits             1155     1328     +173     
- Misses            516      564      +48     

Files Changed	Coverage Δ
mudata/_core/io.py	64.43% <39.18%> (-5.63%)	:arrow_down:
mudata/_core/utils.py	79.06% <60.00%> (-6.65%)	:arrow_down:
mudata/_core/mudata.py	63.86% <80.00%> (+1.19%)	:arrow_up:
tests/test_mod_order.py	100.00% <100.00%> (ø)
tests/test_nullable.py	100.00% <100.00%> (ø)
tests/test_repr.py	100.00% <100.00%> (ø)
tests/test_view_copy.py	100.00% <100.00%> (ø)