Extract the kafka streams and flink use case and load generator
and commons dependencies to a convention plugin to reduce the
complexety of the main build gradle file.

Create convention plugins to reduce complexity of the root build.gradle file

Co-authored-by: Nico Biernat <stu209212@mail.uni-kiel.de>

- Added application-kafkastreams-common project
- modified root gradle project
- configure eclipse quality tools and formatting