Goal is that an eZ Publish developer can build a website using Twig templates without needing to write an identical pagelayout in the legacy template system simply to support legacy-only modules and view.

• Add an option to specify a twig-based legacy template layout in parameters.yml
• Modify LegacyKernelController to use this option to render module results if it's specified.
• Modify the legacy ezpKernelWeb to return the module_result information in addition to the rendered content to support this new ability.