chore: add ManagedReference YAML roundtrip tests

Author: filzrev

src/Docfx.Common/Json/JsonUtility.cs

@@ -91,9 +91,11 @@ private static bool IsSupported()
             switch (fullName)
             {
                 case "Docfx.Build.Engine.XRefMap":
-                case "Docfx.DataContracts.ManagedReference.PageViewModel":
                     return true;
 
+                case "Docfx.DataContracts.ManagedReference.PageViewModel":
+                    return false; // TODO: Need to support ExtensionData
+
                 // Intermediate types for tests. it's expected to be removed later (And return true by default).
                 case "Docfx.Plugins.MarkdownServiceProperties":
                     return true;

test/docfx.Tests/SerializationTests/YamlSerializationTest.ManagedReference.cs

@@ -19,6 +19,6 @@ public void YamlSerializationTest_ManagedReference(string path)
 
         // Act/Assert
         ValidateYamlRoundTrip(model);
-        ValidateYamlJsonRoundTrip(model);
+        ValidateYamlJsonRoundTrip(model);       
     }
 }