Add benchmark implementations for Apache Beam

Branch apache-beam which contains the work of @stu128012's Bachelor's thesis will serve as a basis.

added modul/benchmarks label

mentioned in issue #165

mentioned in issue #21 (closed)

created merge request !102 (closed) to address this issue

mentioned in merge request !102 (closed)

changed the description

assigned to @stu203404

mentioned in merge request !187 (merged)

mentioned in issue #278 (closed)

closed with merge request !187 (merged)

mentioned in commit e14323d5