Add package sticker

[IndrajeetPatil]

Closes #1188

• Include the sticker in README
• Generate favicons for pkgdown
• Include script used to generate sticker and ignore it for build

Needs to wait for #2510

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bad1632) 98.55% compared to head (e2b4dd0) 98.55%.

❗ Current head e2b4dd0 differs from pull request most recent head e9ae585. Consider uploading reports for the commit e9ae585 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2511   +/-   ##
=======================================
  Coverage   98.55%   98.55%           
=======================================
  Files         126      126           
  Lines        5762     5762           
=======================================
  Hits         5679     5679           
  Misses         83       83           

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