Make workload generator object-oriented

Could also fit into @stu202077's tasks

mentioned in issue #16 (closed)

added modul/benchmarks/load-generator label

mentioned in merge request !6 (merged)

mentioned in merge request !28 (merged)

changed milestone to %0.2.0

closed via merge request !6 (merged)

mentioned in commit 5777c722

mentioned in commit 351b9ec6