merge from 1.5 to 3.0

fix: fix bugs caused by 1.5

Ftr/self discovery

Ftr:  Use invoker with same ip as client first.

Ftr:  Add an "api way" to set general configure

Fix/graceful shutdown

Ftr: registry ip:port set from enviroment variable

fix:nacos service provider does not require subscribe

Format go.mod for Goland

Bump actions/cache from v2 to v2.1.4

Merge pull request #1048 from apache/dependabot/go_modules/develop/github.com/nacos-group/nacos-sdk-go-1.0.6

Bump github.com/nacos-group/nacos-sdk-go from 1.0.5 to 1.0.6

Update dubbo_invoker.go

Imp: destroy invoker smoothly

Rft: remove trailing whitespace

docs: fix grammar and fix links