Issue #2373735 by joelpittet, dawehner: Simplify/clean up BareHtmlPageRenderer

core/authorize.php

core/includes/batch.inc

core/includes/errors.inc

core/includes/install.core.inc

...rupal/Core/EventSubscriber/DefaultExceptionSubscriber.php

...Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php

core/lib/Drupal/Core/Render/BareHtmlPageRenderer.php

.../lib/Drupal/Core/Render/BareHtmlPageRendererInterface.php

core/modules/system/src/Controller/DbUpdateController.php