News: https://developers.line.biz/en/news/2021/01/20/messaging-api-update-january-2021/ - [x] [Get narrowcast message status properties to know acceptedTime and completedTime](https://developers.line.biz/en/reference/messaging-api/#get-narrowcast-progress-status) - [x] [Text message type properties to support user-mention](https://developers.line.biz/en/reference/messaging-api/#wh-text)
