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

Conflicts:
- `app/controllers/api/v1/statuses_controller.rb`:
  Conflict due to upstream adding a new parameter (with_rate_limit),
  too close to glitch-soc's own additional parameter (content_type).
  Added upstream's parameter.
- `app/services/post_status_service.rb`:
  Conflict due to upstream adding a new parameter (rate_limit),
  too close to glitch-soc's own additional parameter (content_type).
  Added upstream's parameter.
- `app/views/settings/preferences/appearance/show.html.haml`:
  Conflict due to us not exposing theme settings here (as we have
  a different flavour/skin menu).
  Took upstream change, while still not exposing theme settings.
- `config/webpack/shared.js`:
  Coding style fixes for a part we have rewritten.
  Discarded upstream changes.

config/webpack/shared.js

@@ -98,7 +98,7 @@ module.exports = {
         // temporary fix for https://github.com/ReactTraining/react-router/issues/5576
         // to reduce bundle size
         resource.request = resource.request.replace(/^history/, 'history/es');
-      }
+      },
     ),
     new MiniCssExtractPlugin({
       filename: 'css/[name]-[contenthash:8].css',