[java] Add PolarStreams as a new platform in the OpenMessaging Benchmark Framework

[jorgebay]

We should add PolarStreams as a new platform on the OpenMessaging Benchmark Framework, that way we can compare against other event streaming platforms.

https://openmessaging.cloud/docs/benchmarks/#adding-a-new-platform
https://github.com/openmessaging/benchmark

I think the project uses JDK 8, so it won't be possible to use the modern java's HttpClient to produce messages in Barco Streams.