feat(controllers): add attribute to disable the routing convention

Author: jaredcnance

src/JsonApiDotNetCore/Controllers/DisableRoutingConventionAttribute.cs

@@ -0,0 +1,7 @@
+using System;
+
+namespace JsonApiDotNetCore.Controllers
+{
+    public class DisableRoutingConventionAttribute : Attribute
+    { }
+}