Webpack 5 🏎

[marcelgerber]

Webpack 5 it is, since it speeds up builds quite a lot.

A warm (with cache) Webpack development build with small changes now takes a mere 7 seconds, and a production build is down to 24s 🚀

There are still a few things to do or wait for:

• Update to Webpack 5
  • Wait for Webpack 5 RC (webpack 5 release plan webpack/webpack#11406)
• Update to webpack-cli 4.0
  • Currently blocked by webpack serve fails with TypeError: cli.commandLineArgs is not a function webpack/webpack-cli#1814
  • Somehow that update seems to have disabled caching? For yarn webpack serve cache files are written to disk, but not for yarn webpack? (Project with webpack-cli@4.0.0-rc.0 doesn't use cache webpack/webpack-cli#1842)
• Enable Webpack 5 persistent caching
• Wait for dotenv-webpack Webpack 5 support (feat: supporting webpack 5 mrsteele/dotenv-webpack#234)
  • Revert changes to settings.ts after upgrading dotenv-webpack
• Switch away from filenamify, since it requires path
  • Alternatively, wait for Add the possibility to use filenamify with webpack 5, without adding a path polyfill sindresorhus/filenamify#16
  • Alternative, use a fork of the project
• Switch away from csv-parse, since it requires Buffer
• Update Storybook config to also work with Webpack 5
  • Wait for webpackVersion check doesn't work if multiple versions of webpack are in use webpack-contrib/mini-css-extract-plugin#600 to be fixed
• Consolidate commits
• Go through deprecation warnings (most likely caused by Webpack loaders/plugins that are not yet compatible)
  • Maybe find a replacement for the deprecated webpack-manifest-plugin
• Go through cache warnings
• Consolidate commits
• Look out for regressions on staging

The changes csv-parse -> papaparse and filenamify -> sanitize-filename are needed because Webpack 5 removes automatic Node polyfills.
We could still manually polyfill those, but I thought it to be cleaner to use browser-first modules instead.

[marcelgerber]

Let's close this now since it's gone very stale - we can revisit this at some point in the future (and of course use this PR for reference), or maybe we want to switch away from Webpack after all at some point.