Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- app/controllers/settings/follower_domains_controller.rb
  Removed upstream. Did the same here. Maybe we should not have?
- config/locales/en.yml
  Upstream removed the “Authorized followers” page and associated
  translations. This is too close in the file to our glitch-soc-specific
  “flavour” string. No actual conflict.
- config/locales/ja.yml
  Same as above.
- config/locales/pl.yml
  Same as above.
- config/navigation.rb
  No real conflict. New route added too close to the glitch-soc-specific
  “flavours” one.
- config/webpack/configuration.js
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- config/webpack/loaders/babel.js
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
  The contents of this file have been moved to package.json.
- config/webpack/shared.js
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- config/webpacker.yml
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- jest.config.js
  The contents of this file have been moved to package.json.
- package.json
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.
- yarn.lock
  Upstream refactored the webpack(er) configuration quite a bit.
  Tried to keep up.

config/webpack/rules/css.js

@@ -0,0 +1,31 @@
+const MiniCssExtractPlugin = require('mini-css-extract-plugin');
+
+module.exports = {
+  test: /\.s?css$/i,
+  use: [
+    MiniCssExtractPlugin.loader,
+    {
+      loader: 'css-loader',
+      options: {
+        sourceMap: true,
+        importLoaders: 2,
+        localIdentName: '[name]__[local]___[hash:base64:5]',
+      },
+    },
+    {
+      loader: 'postcss-loader',
+      options: {
+        sourceMap: true,
+      },
+    },
+    {
+      loader: 'sass-loader',
+      options: {
+        includePaths: ['app/javascript'],
+        fiber: require('fibers'),
+        implementation: require('sass'),
+        sourceMap: true,
+      },
+    },
+  ],
+};