Merge branch 'featue/addCommentForMetadata' of https://github.com/watermelo/dubbo-go into featue/addCommentForMetadata

Mod: update the comments in metrics

Mod: modify file name metedata to metadata

Add comments for config_center

Add attribute method into Invocation and RpcInvocation

Opt: opt err handling

Add comments for common directory

Merge branch 'featue/addCommentForCommon' of https://github.com/watermelo/dubbo-go into featue/addCommentForCommon

remove lock from url

Fix: gitee code analysis shadow err

Opt: optimize url to string

Ftr: Add integrate test

Sync latest Develop

Revert "Fix docker ci bug"

Fix docker ci bug