[pagex] implement visibility flags

[voidcannon] migrate to visibility flags

content/authors/testauthor.pagex.js

@@ -1,4 +1,4 @@
-import {VoidcannonContentType} from "voidcannon";
+import {VoidcannonContentType, VoidcannonVisibilityFlags} from "voidcannon";
 
 export default {
     type: VoidcannonContentType.AUTHOR,
@@ -17,5 +17,8 @@ export default {
             url: "https://blog.bignut.zip/",
             icon: "public"
         }
-    ]
+    ],
+    visibility_flags: [
+        VoidcannonVisibilityFlags.HIDDEN_IN_SITEMAP,
+    ],
 }