List message templates

{  "items": [    {      "id": "497f6eca-6276-4993-bfeb-53cbbbba6f08",      "displayName": "string",      "status": "string",      "versions": [        {          "id": "497f6eca-6276-4993-bfeb-53cbbbba6f08",          "version": 0,          "status": "string",          "variableDefinitions": [            {              "name": "string",              "type": "text",              "required": true            }          ],          "customerPreview": "string",          "creditCostPerSend": 0,          "createdAt": "string",          "readyAt": "string",          "disabledAt": "string"        }      ]    }  ]}