JetBrains plugin: Make Java/Kotlin decision

Created by: vdavid

Random notes:

• Kotlin seems to be a lot closer to JS than Java
• Our existing plugin is written in Java, as well as Coury's branch
• No research on the JS aspect as well
• We (the G&I team) woudl prefer this to be a collaborative act rather than a one-man show, and none of us is very experienced in Java or Kotlin. Doing it in TypeScript somehow would be best from this angle.