Expose includeStaticFiles configuration option to MapTopicErrors()

The `MapTopicErrors()` extension method is one way to configure routing to the `ErrorController`. It isn't the _only_ approach, but it is the one that provides easiest access to the main variables that implementers are likely to want to change, such as the base URL. This is now extended to optionally accept an `includeStaticFiles` parameter, which maps to the parameter of a corresponding name on the `Http` action itself (83f4691). If set to `false`, static files won't return a custom error page—or, rather, will get one, but it will only contain a very lightweight, canned message. This satisfies the configuration requirements of Feature #101.

Author: JeremyCaney

OnTopic.AspNetCore.Mvc/ServiceCollectionExtensions.cs

@@ -221,11 +221,18 @@ public static void MapImplicitAreaControllerRoute(this IEndpointRouteBuilder rou
     ///   StatusCodePagesExtensions.UseStatusCodePages(IApplicationBuilder)"/>, by providing a route for capturing the <c>
     ///   errorCode</c>.
     /// </remarks>
-    public static ControllerActionEndpointConventionBuilder MapTopicErrors(this IEndpointRouteBuilder routes, string rootTopic = "Error") =>
+    /// <param name="routes">The <see cref="IEndpointRouteBuilder"/> this route is being added to.</param>
+    /// <param name="rootTopic">The name of the root topic that the route should be mapped to. Defaults to <c>Error</c>.</param>
+    /// <param name="includeStaticFiles">Determines if static resources should be covered. Defaults to <c>true</c>.</param>
+    public static ControllerActionEndpointConventionBuilder MapTopicErrors(
+      this                      IEndpointRouteBuilder           routes,
+      string                    rootTopic                       = "Error",
+      bool                      includeStaticFiles              = true
+    ) =>
       routes.MapControllerRoute(
         name: "TopicError",
         pattern: $"{rootTopic}/{{id:int}}/",
-        defaults: new { controller = "Error", action = "Http", rootTopic }
+        defaults: new { controller = "Error", action = "Http", rootTopic, includeStaticFiles }
       );
 
     /*==========================================================================================================================