PIP 28: Improve pulsar proxy log messages

[sun yao]

Hi folks,
      Pulsar Proxy is almost a gateway for all pulsar requests, it would be 
helpful if it can record more details for the traffic, like source, target, 
session id, response time(different stage) for each request, even for message 
body.       I am proposing an improve for pulsar proxy, for more information :  
           PIP: 
https://github.com/apache/pulsar/wiki/PIP-28%3A-Improve-pulsar-proxy-log-messages
                  Feel free to let me know any ideas or suggestions for this 
feature.          Thanks.