Add customizable user roles (#18641)

* Add customizable user roles

* Various fixes and improvements

* Add migration for old settings and fix tootctl role management

app/controllers/custom_css_controller.rb

@@ -13,6 +13,6 @@ class CustomCssController < ApplicationController
   def show
     expires_in 3.minutes, public: true
     request.session_options[:skip] = true
-    render plain: Setting.custom_css || '', content_type: 'text/css'
+    render content_type: 'text/css'
   end
 end