Fix interaction between NormalResult and shared namespace (#790)

One-line fix to Rust code generation when using both CLI --shared option
and Result co-type

Author: jrdouceur

codegen/src/Azure.Iot.Operations.ProtocolCompiler/EnvoyGenerator/EnvoyTransformFactory.cs

@@ -320,7 +320,7 @@ private static IEnumerable<ITemplateTransform> GetCommandTransforms(string langu
 
                     if (normalResultSchema != null)
                     {
-                        yield return new RustSerialization(respSchemaNamespace ?? genNamespace, genFormat, normalResultSchema, workingPath);
+                        yield return new RustSerialization(normalResultNamespace ?? genNamespace, genFormat, normalResultSchema, workingPath);
                     }
 
                     break;