Closes: #290 - Expose table_model_name and object_type_name in CustomObjectType API response

[bctiemann]

Closes: #290

Adds table_model_name and object_type_name to the API response for CustomObjectTypes, as a convenience for the use of client-side scripts consuming object_types and needing to map them to Custom Object Types via their internal model name.

                    "is_cloneable": false,
                    "comments": ""
                }
            ],
            "table_model_name": "Table3Model",
            "object_type_name": "netbox_custom_objects.table3model"
        },