• Separate versioning of sbt-scalafix and scalafix-core similar to sbt-scalafmt and scalafmt-core. Users should declare the Scalafix version in .scalafix.conf so that clients like Metals or maybe IntelliJ can load the correct version of Scalafix without having to inspect project/plugins.sbt

• It will make easier the release of scalafix, which is now depending on sbt-scalafix.

#fixes #1084