Add sonar check for ratis

As elek added the Github based post commit checks in RATIS-697, we can also add the Sonar check to continuously inspect the code quality and improve.

I have already reached out to INFRA and got the incubator-ratis project added to Apache's Sonar Cloud.

Further, all folks who had access to Ozone Sonar Cloud will already be given access to Ratis Sonar Cloud instance by default.

This Jira aims to enable the sonar check via Github.