Resolve #3483304 Allow disabling page displays for node types

Closes #3483304

core/config/schema/core.entity.schema.yml

@@ -70,6 +70,9 @@ core.entity_view_display.*.*.*:
       sequence:
         type: boolean
         label: 'Value'
+    pageDisplay:
+      type: boolean
+      label: 'Add a page display for this view mode'
 
 field_formatter:
   type: mapping