Migrate dsbenchmark from coretutorials

There already is daily jobs running dsbenchmark tests:
https://jenkins.opendaylight.org/releng/view/mdsal/job/mdsal-csit-1node-periodic-dsbenchmark-only-beryllium/plot/

The python part is in integration/test repository, but the java part is built in coretutorials project.
But, coretutorials project is not participating in Beryllium release cycle.
The snapshot artifacts are available in Nexus artifacts, but for Autorelease purposes integration/distribution will remove coretutorials feature repository on M4 (offset 2), making the test jobs fail for stream=beryllium.

Dsbenchmark implementation exercises APIs from Controller project, which is part of Beryllium; so Controller is good project to host dsbenchmark code going forward.
There are other *benchmark components in Coretutorials, but their migration can wait until there are (Lithium) tests that actually use them.

Note: stable/lithium branch of coretutorials may have more recent code than master branch.