Feature Request: depridate Json4s, add Jsoniter

[andyczerwonka]

Json4s is the worst performing JSON library in the Scala ecosystem. It would be nice to have options within the ScalaPB to emit JSON using a more widely accepted library, be that jsoniter, circe, upickle, etc

[thesamet]

Hi @andyczerwonka , this is not maintained by me, but have you looked into this set of repos https://github.com/scalapb-json ?