WEBDEV-9442: Move the iaux-icons set into the icons folder

[jbuckner]

Stacked on #167, since some of these icons already exist there. Part of WEBDEV-9432. Ported from @internetarchive/icon-* 1.4.1.

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https://claude.ai/code/session_018RNLPbA9rJzrvHRvAccYcf

[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://internetarchive.github.io/elements/pr/pr-173/
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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.58%. Comparing base (222773b) to head (4d25a4b).

Additional details and impacted files

@@                    Coverage Diff                     @@
##           WEBDEV-9445-element-icons     #173   +/-   ##
==========================================================
  Coverage                      90.58%   90.58%           
==========================================================
  Files                             93       93           
  Lines                           3336     3336           
  Branches                         799      799           
==========================================================
  Hits                            3022     3022           
  Misses                           131      131           
  Partials                         183      183           

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