Added executable scripts for benchmarks and stresstest

[lukas-mazur]

Two executable scripts have been added in sub-folder bin/

• bin/benchmarks: Performs all memory bandwidth and peakflop tests on all GPUs within a node
• bin/stresstest: Performs stresstest on all GPUs within a node

[carstenbauer]

The new io keyword arguments should ideally be documented (in the docstrings of the functions). At least for those functions, where we already have a list of keyword arguments.

I think the peakflops_gpu_wmmas and peakflops_gpu_fmas functions should also get the io keyword argument. (More generally, it's not ideal that we only introduce io for an rather arbitrary subset of the functions. E.g., the stresstest functions didn't get the new keyword for no apparent reason. But we can live with that of course.)

As for the logging stuff, I've never seriously used the Loggers before so I can't really comment on how to properly use them and I'm fine with the executable scripts as is. Let me note though that there certainly is a FileLogger or similar in the ecosystem as well (see, e.g., https://github.com/JuliaLogging/LoggingExtras.jl).

[lukas-mazur]

@carstenbauer I agree with your points. I should have fixed now all the points you have mentioned. If I have missed something, please let me know.