Walk directories in sorted order for reproducibility

[dalcinl]

Implement a new utility function wrapping os.walk with the following modifications:

• recurse directories in sorted order
• recurse top-level *.dist-info/ directories last
• list filenames in sorted order
• list top-level *.dist-info/RECORD files last

[dalcinl]

There is an additional nit that would be trivial to address in this PR. Currently, auditwheel outputs zip files using the usual convention of storing directories as an entry of zero bytes with name ending in "/". This is exactly what the zip utility does in Linux, but it is not what the wheel package does (and causes trouble with namespace packages).

What we could do (with a one-line change in this PR) is to still store subdirectories, but only if they are empty. Again, this is not what zip or python -m zipfile do. However, it is closer to what wheel does, albeit without the issue related to namespace packages. There is a minor backward incompatibility in the sense that the output zip files would no longer have all directory entries, but only those directories that are empty. However, upon unzipping, there would be no difference in the output directory tree. BTW, the wheel file spec says nothing about empty directories.

[dalcinl]

This PR covers #507 and provides additional features (.dist-info directories last, .dist-info/RECORD files last)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.47%. Comparing base (2e00860) to head (457be20).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #517      +/-   ##
==========================================
+ Coverage   92.35%   92.47%   +0.12%     
==========================================
  Files          20       20              
  Lines        1268     1289      +21     
  Branches      244      250       +6     
==========================================
+ Hits         1171     1192      +21     
  Misses         56       56              
  Partials       41       41              

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[mayeut]

Removing entries for non-empty folders also removes the permissions attribute for those. I'm gonna revert this for now.

[dalcinl]

@mayeut Maybe you want to keep the test for empty folders?

[mayeut]

thanks @dalcinl