Extended 'validationDelegate to remove List` topics

There is no scenario where we expect a `List` topic to be included in the navigation—or, generally, for the children of `List` topics to be included, and especially since a `List` cannot be navigated to. If we did, that would be a highly specialized scenario, and would necessitate a custom `validationDelegate()` to handle that logic. As such, we should strip `List` topics out of the default `MenuViewComponentBase<T>` so that they don't need to be explicitly filtered out at the view level, as they are today.

(This also makes a minimal gain in terms of memory and performance since these unnecessary topics don't need to be mapped or cached in memory. That's likely negligible, of course.)

Author: JeremyCaney

OnTopic.AspNetCore.Mvc/Components/MenuViewComponentBase{T}.cs

@@ -102,7 +102,7 @@ IHierarchicalTopicMappingService<T> hierarchicalTopicMappingService
       await HierarchicalTopicMappingService.GetRootViewModelAsync(
         navigationRootTopic!,
         3,
-        t => t is not { Parent: { ContentType: "PageGroup" } }
+        t => t is not { ContentType: "List" } and not { Parent: { ContentType: "PageGroup" } }
       ).ConfigureAwait(false);
 
     /*==========================================================================================================================