Merge commit '7335a43b6dac0e82c305ce4dec9db4da114c769e' into glitch-soc/merge-upstream

Conflicts:
- `app/helpers/application_helper.rb`:
  Upstream reworked how CSS classes for the document's body are computed.
  Slight conflict due to glitch-soc's different theming system.
  Updated as upstream did.

app/controllers/settings/base_controller.rb

@@ -4,15 +4,10 @@ class Settings::BaseController < ApplicationController
   layout 'admin'
 
   before_action :authenticate_user!
-  before_action :set_body_classes
   before_action :set_cache_headers
 
   private
 
-  def set_body_classes
-    @body_classes = 'admin'
-  end
-
   def set_cache_headers
     response.cache_control.replace(private: true, no_store: true)
   end