Use OpenSergo with Sentinel Go

Sentinel is a cloud-native traffic governance component that takes "flow" as the breakthrough point and covers multiple fields including rate limiting, concurrency limiting, circuit breaking, and adaptive overload protection to guarantee the reliability of microservices.

Sentinel Go provides data-source module, which provides integration with OpenSergo spec. Please refer https://github.com/alibaba/sentinel-golang/pull/489 for work-in-progress version.