Allow configuring of page_layout for full view mode

Problem/Motivation

CustomElementsRenderer::renderResponse hardcodes the page_layout property. This can be then overridden with either hook_lupus_ce_renderer_response_alter or with a request attribute $request->attributes->get('lupus_ce_renderer_response_data').

It would be helpful to allow frontend to be in control by allowing the page_layout property for full view mode.