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.

app/views/settings/preferences/appearance/show.html.haml

@@ -1,7 +1,10 @@
 - content_for :page_title do
   = t('settings.appearance')
 
-= simple_form_for current_user, url: settings_preferences_appearance_path, html: { method: :put } do |f|
+- content_for :heading_actions do
+  = button_tag t('generic.save_changes'), class: 'button', form: 'edit_user'
+
+= simple_form_for current_user, url: settings_preferences_appearance_path, html: { method: :put, id: 'edit_user' } do |f|
   .fields-group
     = f.input :locale, collection: I18n.available_locales, wrapper: :with_label, include_blank: false, label_method: lambda { |locale| human_locale(locale) }, selected: I18n.locale, hint: false