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/helpers/admin/settings_helper.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Admin::SettingsHelper
+  def site_upload_delete_hint(hint, var)
+    upload = SiteUpload.find_by(var: var.to_s)
+    return hint unless upload
+
+    link = link_to t('admin.site_uploads.delete'), admin_site_upload_path(upload), data: { method: :delete }
+    safe_join([hint, link], '<br/>'.html_safe)
+  end
+end