swap shakapacker for jsbundling-rails

[Lordnibbler]

Todo

• build with webpack
• url('~../images/home/experience-figure.svg')
• get sprockets working to serve built bundle
  • inverse tutorial https://andre.arko.net/2020/07/09/rails-6-with-webpack-in-appassets-and-no-sprockets/
• fonts
• other bundles, contact me, photography, custom
• tutorial for hot reload, and more advanced webpack config https://blog.wilbertaristo.com/webpacker-to-jsbundling-rails-migration
• remove all references to webpacker/shakapacker
• tests
  • make sure build runs before tests (step 5 here https://hybrd.co/posts/migrating-from-webpacker-to-the-new-bundling-approach)
• CI