Fix for GPencil and Cycles Render draw type. GPencil objects were only shown when overlays were turned on. The cause of this is an optimization we did to not populate any draw engine when an external renderer was used with overlays turned off. This will check if there is any visible GPencil object in the scene. if so it will still perform the loop. `DEG_id_type_any_exists` can check if any object of a certain type_id is in the result. This check is also being used to check if there are any visible grease pencil objects as a precheck in `DRW_render_check_grease_pencil`. Reviewed By: brecht, fclem, antoniov Maniphest Tasks: T65191 Differential Revision: https://developer.blender.org/D4962