Support Scalafix migrations in Scala CLI projects

[fthomas]

Scala CLI 1.5.4+ will contain a scalafix command (VirtusLab/scala-cli#2968) which we should be able to use for implementing ScalaCliAlg#runMigration which is currently a NOP.

Full support for Scalafix migrations is currently only available for sbt projects. The corresponding code in SbtAlg can be used as inspiration for supporting them in Scala CLI.

[Gedochao]

Actually, it will ship in Scala CLI 1.6.0, just FYI.
It's available in the recent nightly, but the syntax is still likely to change considerably (track VirtusLab/scala-cli#3327) before I release 1.6.x