Scala Installations support

Adds a valid, persistent, best-effort scala library bundle setup on classpath after the choice of a scala desired source level in project-scopes compiler options.

Operates by modifying and serializing the scala classpath container.

Does not include scala-installation registry edition yet.
This classpath is added to the project classpath, to be sure that the runtime classpath contains all the classes needed by the REPL. So it is not needed to add the compiler jar to a simple Scala project to be able to use the REPL.