Enhance Gradle Logic Sharing between Projects

The gradle docs encourage sharing cross configurations with convention plugins. The actual way using subproject is discouraged.

Interesting discovery, let's discuss in person, okay? :)

added modul/benchmarks modul/benchmarks/load-generator labels

mentioned in merge request !90 (merged)

mentioned in merge request !95 (merged)

added modul/benchmarks/flink modul/benchmarks/kstreams labels

closed with merge request !95 (merged)

mentioned in commit f6f7fa31