Add icons for .apng and .avif

[nix6839]

Add icons for .apng and .avif.

TODO

• Use cargo fmt
• Add necessary tests
• Update default config/theme in README (if applicable)
• Update man page at lsd/doc/lsd.md (if applicable)

[muniu-bot]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.63%. Comparing base (e9a778a) to head (6b7bc09).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1007   +/-   ##
=======================================
  Coverage   84.63%   84.63%           
=======================================
  Files          53       53           
  Lines        5078     5078           
=======================================
  Hits         4298     4298           
  Misses        780      780           

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[zwpaper]

thanks for the contribution