This commit is intended only for kt-branches where IDEA < 221.

Two reasons to load Kotlin plugin as an artifact instead of flat classpath:
1. It fixes that Kotlin plugin is in the classpath of FIR IDE (FIR IDE
   also uses `community/intellij.idea.community.main.iml` in it's run
   configuration)
2. There is no other better way to make JPS work in debug IDEA. None
   of the options inside `isRunningFromSources` in
   `BuildProcessClasspathManager.Companion#findClassesRoot` will
   work for the Kotlin plugin

GitOrigin-RevId: aa917e2dda26f81e40e3c6bd244cf85a32758153