scala 3: publish scalafix-cli_3

[mlachkar]

Remaining steps before publishing

• check status of WIP: Migrate quasiquote macros to Scala 3 scalameta/scalameta#3347
• many of tests in ScalafixArgumentsSuite rely on semanticRule, and we don't have any yet for scala 3. We need to create a simple semanticrule and test the ignored tests for scala 3 (search for "i1680" in code)
• coursier lookups in scalafix-cli_3 should fallback to loading 2.13 artifacts for requested community rules artfacts not available in scala 3
• do we really need full-cross-version in Scala 3? Consider https://www.scala-lang.org/blog/2022/08/17/long-term-compatibility-plans.html
• publish artifacts (only SNAPSHOTs to start with? how can we prevent cs install to pick up scalafix-cli_3 which has the known limitations of not supporting quasiquotes when loading source rules?)
• document the experimental aspect of the Scala 3 artifacts (quasiquotes can't be used, 2.13 artifacts ending up in the classpath)
• update integration tests
• reenable testing scala latest with Scala 3 build
• scalafix-core: implicit helpers not available with -Xsource:3 on 2.13.13 #1949

Next steps

• advocate for community rules to cross-compile to scala 3 by updating https://github.com/scalacenter/scalafix.g8 & https://scalacenter.github.io/scalafix/docs/developers/cross-publish-custom-rules.html
• make it possible (but not default?) in sbt-scalafix to use scalafix-cli_3 when sources are in scala 3
• drop support for testing Scala 3 targets with Scala 2.12 in https://github.com/scalacenter/scalafix.g8 ?