Added CFREPL team changes from Gitlab & 1Up team plugins

[AbeleMM]

Change-log

• added CodeFeedr plugins developed by 1Up team:
  • Cargo
  • ClearlyDefined
  • JSON
  • Maven
  • npm
• removed some unused imports in existing files (e.g. java.util.Optional in the KafkaBuffer source file);
• ran the scalafmt sbt command to fix static analysis warnings;
• integrated PyPiReleasesSource with the PluginReleasesSource abstract class used by the 1Up plugins in order to minimize code duplication;
• added the option for plugin stages to auto-export their schema to ZooKeeper at startup & enabled it for the following stages:
  • CargoReleasesStage
  • ClearlyDefinedReleasesStage
  • MavenReleasesExtStage
  • MavenReleasesStage
  • NpmReleasesExtStage
  • NpmReleasesStage
  • PyPiReleaseExtStage
  • PyPiReleasesStage
• moved sbt-assembly declaration to project/plugins.sbt where declarations for the other used plugins are present;
• fixed various compilation warnings;
• fixed order of description & link fields for PyPi stages.