Chat API updates

尊敬的开发者，

1.webchat端和app端将支持删除message，而openapi暂时不支持删除。而被删除的message在openapi的v2.sellerchat.get_message接口取回时会显示消息文案。文案的内容为"This message was deleted"，示例如下：

另外需要说明的是，status为Censored whitelist 和 Normal的消息可以被删除，status为auto-reply和censored blacklist的消息不可以被删除，且删除消息的功能目前只在SG,TH,ID,MY可用。

上线时间：2022.4.29

涉及接口：

v2.sellerchat.get_message

Dear developers,

1.webchat and app will support to delete message,but openapi doesn't support now. For deleted message, it will return a text in openapi's v2.sellerchat.get_message whose content text is "This message was deleted", the sample is as below:

There is another thing need to explain that the message whose status is Censored whitelist and Normal can be deleted and whose status is auto-reply and censored blacklist cannot be deleted. Currently delete messages is only available in some regions, not all regions. They are: SG, TH, ID, MY.

Effective Date on Live: 2022.4.29

Related APIs:

v2.sellerchat.get_message