Gromacs EESSI on top of CSCS GROMACS library test

[casparvl]

This PR contains an implementation of the GROMACS library test that comes with ReFrame. We

• Usa a standard set of hooks to skip e.g. GPU tests on CPU nodes, set number tasks per node equal to the number of cores per node, etc
• Tag all tests cases with monitoring and a single test case with CI
• Parametrize for different node counts (1,2,8,16) and tag accordingly with singlenode, n_small, n_medium, n_large.
• Skip running with -nb gpu on CPU based nodes.

[casparvl]

To test:

• Checkout ReFrame-3.9.2 from github (e.g. to ~/reframe)
• Checkout software-layer with this change (e.g. to ~/software-layer)
• If running on the EESSI Magic Castle test cluster, it should run with the config/settings_magic_castle.py config file for ReFrame. On other cluster, adapt the virtual partitions in that config file to match your own cluster. Be sure to list gpu's as devices with name gpu. Specify the processor num_cores config item for each partition. Modify the access item in order to match the scheduler arguments needed for your cluster.
• Run with e.g. PYTHONPATH=$PYTHONPATH:~/reframe/:~/software-layer/tests/reframe/ reframe -C config/settings_magic_castle.py -c eessi-checks/applications/ -r -t CI -t n_small --performance-report (the PYTHONPATH should contain the right dirs in order to find the hpctestlib from ReFrame, and the utils and hooks from the ~/software-layer/tests/reframe/eessi_utils directory)

[hmeiland]

some code in here for gpu; while there is not gpu support in EESSI today; let's make sure we review this again when it becomes available....

[casparvl]

We'll move the tests in a separate repo. Closing in favor of EESSI/test-suite#9