investigate using (almost) all jars and not the sdk tarball

currently we fetch a version of the sdk tarball. This include several jars at a fixed version. It might be better to just use maven published jars as much as possible, since that will make portability across scala versions somewhat easier I think.

Start by reviewing how the SDK tarball is currently fetched and which fixed-version JARs it provides. Compare that approach with using Maven-published JARs, focusing on portability across Scala versions. Done means identifying a concrete dependency strategy and the changes needed to adopt it.

Written by the indexing model from the issue text.