FIX: ITK HDF5 displacement ordering

[oesteban]

Summary

• fix reading of displacement fields from ITK HDF5 files by detecting C-order storage
• remove xfail from regression test

Testing

• pytest -c /dev/null nitransforms/tests/test_io.py::test_itk_h5_field_order -q
• pytest -c /dev/null -q (fails: 140 failed, 67 passed, 14 warnings, 119 errors)

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https://chatgpt.com/codex/tasks/task_e_687dea0dc7548330968169d3f4a9a574

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.80%. Comparing base (3eb8c39) to head (d90b5e5).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
nitransforms/io/itk.py	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #257      +/-   ##
==========================================
- Coverage   95.09%   94.80%   -0.30%     
==========================================
  Files          16       16              
  Lines        1979     1983       +4     
  Branches      265      266       +1     
==========================================
- Hits         1882     1880       -2     
- Misses         77       82       +5     
- Partials       20       21       +1     

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