TensorFlow and Horovod test

[casparvl]

I recreated the TensorFlow tests from #106 in the library-of-tests fromat, and reusing the same standard hooks as I've set up for e.g. GROMACS.

To run this test case:

• Make sure that tests/reframe is in your PYTHONPATH (so that the eessi_utils is found)
• Adjust the attached settings.py for your system (adapt partition names, #CPU cores, #sockets, # GPUs)
• Make sure you have a new enough ReFrame installation (3.6.2 or newer should work)
• Make sure you have a flat module naming scheme (the find_modules logic is used based on the assumption of a flat module naming scheme). Note that it does not have to be the EESSI software stack per se - it could be some locally installed modules, provided that module av Horovod and module av TensorFlow return you respective Horovod and TensorFlow modules.

After that, simply run e.g.

PYTHONPATH=$PYTHONPATH:$(pwd) reframe --config-file=config/settings_cartesius.py --checkpath eessi-checks/applications/tensorflow2.py -r --performance-report

in the software-layer/tests/reframe directory.

[boegel]

@casparvl Is this still relevant, especially with EESSI/test-suite#38?

I've just introduced 2021.12 and 2023.04 branches, and would like to get rid of the main branch.

[casparvl]

Closing this PR. We now have a native TensorFlow distributed test through EESSI/test-suite#38 . This PR (#122) has a TensorFlow test which uses Horovod for distribution. That's nice, if you want to test Horovod, but we can always re-implement that later in the EESSI test suite.