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 is likely wrong if the project is using a different Scala installation than the platform. I think it should use the jars of the project.
We should create a ticket for that, and fix it when the basic support is merged in.