Add configurability to Java benchmarks

[calderast]

The Java Engineering team at Microsoft is using some of the TechEmpower framework benchmarks to test the performance of our JDK.
We've run into a few places where it would be helpful to add configurability to the Java benchmarks:

• It would be helpful to be able specify the JDK under test
• It would be helpful to be able to append JVM arguments/override existing JVM arguments (see example here for the spring benchmark)
• It would be helpful for the user to be able to specify extra docker arguments (I submitted PR Add option for extra docker args to tfb script #7977 for this, but after a second look I'm not sure if those args actually go to to the docker container under test, or just an intermediate container)

Please let me know if you have any thoughts on how to tackle these issues in a way that would benefit everyone using these benchmarks!

[NateBrady23]

Ah, yes. Now that I think about it, those args are just getting tossed to the toolset container.

I think what would need to happen is a new toolset arg here to pass docker arguments to the test docker container.

We don't have any bandwidth to add new features to the toolset right now, but certainly if somebody wants to tackle this, I'll give guidance where I can.