Reinstate .styl noop replacement for production webpack builds

[bjester]

Summary

Re-adds module replacement in the webpack config for Vuetify's stylus files, but more specifically only targeting .styl files. Without this specificity, other resolution failures occur for mini-css-extract-plugin/dist/hmr/hotModuleReplacement.js, which was the original cause for removal during the pnpm transition.

References

source #4106
closes #5342

Reviewer guidance

1. Edit the webpack config to always use the devserver output path
2. Run npx webpack serve --env prod --config webpack.config.js --progress and pnpm run runserver
3. Check studio UI for RTL lang

[rtibbles]

Manual testing checks out. I can't for the life of me remember how this works, but hopefully we'll just get rid of Vuetify and I'll never have to remember!