[Feature] Json format data response

[duongxinh2003]

新增功能的使用场景

When you use JsonDataCodec for codec protocol, you must convert byte array to JSON data and use it. For example: A request you send from the client has pattern (following by example github example ):

{"cmdCode":1,"cmdMerge":1245185,"data":{"name":"英雄无敌-3"}}

1. The response data is a byte array: [123,34,110,...]
2. The first convert byte data is:

   {
   "cmdCode": int,
   "cmdMerge": int,
   "data": byte[],
   "msgId": int,
   "protocolSwitch": int,
   "responseStatus": int
   }

   You must convert this byte[] at data field to use it. It takes 2 times to transform data in the client to use it, you can convert data to JSON and serialize it before sending to the client instead. Example:

   {
   "cmdCode": int,
   "cmdMerge": int,
   "data": {"name": String}
   "msgId": int,
   "protocolSwitch": int,
   "responseStatus": int
   }

[iohao]

By default, you can get a unified behavior, which can be well compatible when switching protocols, such as switching between json, prootbuf, or other protocols.

If the situation is special, it is recommended to rewrite MessageToMessageCodec to implement this part of the customization.

[duongxinh2003]

I closed the issue because some languages have libraries that can convert directly like Java, C#,...