[Golang] Implement xlang string for furygo

[LiangliangSui]

Is your feature request related to a problem? Please describe.

The current string implementation protocol in furygo is different from the xlang protocol.

Describe the solution you'd like

We need to implement it in furygo according to the design format of string in xlang protocol.

Additional context

https://github.com/apache/fury/pull/1413