Move theme-related helper methods out of controller (#37807)

app/controllers/application_controller.rb

@@ -17,9 +17,6 @@ class ApplicationController < ActionController::Base
 
   helper_method :current_account
   helper_method :current_session
-  helper_method :current_theme
-  helper_method :color_scheme
-  helper_method :contrast
   helper_method :single_user_mode?
   helper_method :use_seamless_external_login?
   helper_method :sso_account_settings
@@ -173,20 +170,6 @@ class ApplicationController < ActionController::Base
     @current_session = SessionActivation.find_by(session_id: cookies.signed['_session_id']) if cookies.signed['_session_id'].present?
   end
 
-  def current_theme
-    return Setting.theme unless Themes.instance.names.include? current_user&.setting_theme
-
-    current_user.setting_theme
-  end
-
-  def color_scheme
-    current_user&.setting_color_scheme || 'auto'
-  end
-
-  def contrast
-    current_user&.setting_contrast || 'auto'
-  end
-
   def respond_with_error(code)
     respond_to do |format|
       format.any  { render "errors/#{code}", layout: 'error', status: code, formats: [:html] }