[feat-request]: autoselect by lowest latency as an option

System and Shadowsocksx-NG-R8 version:

• Shadowsocksx-NG-R8 1.5.1

Feature Request

let the autoselect by lowest latency step after the delay test, be an option.

e.g.
Some of my routes ping super fast, but they may not be connecting to the internet. (they are just NAT servers)
Or some routes ping fast but with low bandwidth. (they are just backups, won't be used daily).