WEBDEV-9447: Move the BookReader icons into the icons folder

[jbuckner]

Stacked on #178, to dedupe against the earlier sets. Part of WEBDEV-9432. Ported from @internetarchive/bookreader 5.0.0-87.

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https://claude.ai/code/session_013z5wkYSgsvUFKvqY2okZBP

[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://internetarchive.github.io/elements/pr/pr-179/
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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.58%. Comparing base (51b8d79) to head (e9f2d78).

Additional details and impacted files

@@                          Coverage Diff                          @@
##           WEBDEV-9446-collection-browser-icons     #179   +/-   ##
=====================================================================
  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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