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/babel.js

@@ -0,0 +1,22 @@
+const { join, resolve } = require('path');
+const { env, settings } = require('../configuration');
+
+module.exports = {
+  test: /\.(js|jsx|mjs)$/,
+  include: [
+    settings.source_path,
+    ...settings.resolved_paths,
+  ].map(p => resolve(p)),
+  exclude: /node_modules/,
+  use: [
+    {
+      loader: 'babel-loader',
+      options: {
+        sourceRoot: 'app/javascript',
+        cacheDirectory: join(settings.cache_path, 'babel-loader'),
+        cacheCompression: env.NODE_ENV === 'production',
+        compact: env.NODE_ENV === 'production',
+      },
+    },
+  ],
+};