Stage lammps and cp2k data using fixture

[casparvl]

Closes #201

[smoors]

actually, for CP2K we don't need a fixture at all (unless i'm missing something?).
the src directory is automatically staged by reframe, so the only thing we have to do is rename the input directory to src, remove prerun_cmds, and fix executable_opts.

i'll make a PR for is.

UPDATE: #207

[casparvl]

Ok, this PR should not be merged until we come up with a general strategy for deduplication of input files between test cases. Let's have the discussion here #207 (review)

[casparvl]

Ok, I following up on the discussion in #207 , I think we should indeed explore an option to make this happen within EESSI_Mixin. However, to tackle the issues with currently running the daily tests, I'd like to get this PR merged as a bug fix. Just like when implementing EESSI_Mixin itself, we can later always adopt a solution provided by EESSI_Mixin and get rid of this logic in the specific tests.

[smoors]

for reference, this is the error i got with the original PR:

Traceback (most recent call last):
  File "/vscmnt/brussel_pixiu_data/_data_brussel/100/vsc10009/reframe/eessitestsuite/venv_refr4.6.2/lib64/python3.9/site-packages/reframe/frontend/loader.py", line 206, in load
_from_file
    util.import_module_from_file(filename, force, parent)
  File "/vscmnt/brussel_pixiu_data/_data_brussel/100/vsc10009/reframe/eessitestsuite/venv_refr4.6.2/lib64/python3.9/site-packages/reframe/utility/__init__.py", line 117, in imp
ort_module_from_file
    return _do_import_module_from_file(filename, module_name)
  File "/vscmnt/brussel_pixiu_data/_data_brussel/100/vsc10009/reframe/eessitestsuite/venv_refr4.6.2/lib64/python3.9/site-packages/reframe/utility/__init__.py", line 69, in _do_
import_module_from_file
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/vscmnt/brussel_pixiu_data/_data_brussel/100/vsc10009/reframe/eessitestsuite/test-suite/eessi/testsuite/tests/apps/cp2k/cp2k.py", line 10, in <module>
    from eessi.testsuite.tests.apps.cp2k.cp2k_staging.cp2k_stage_input import EESSI_CP2K_stage_input
  File "/data/brussel/100/vsc10009/reframe/eessitestsuite/test-suite/eessi/testsuite/tests/apps/cp2k/cp2k_staging/cp2k_stage_input.py", line 6, in <module>
    class EESSI_CP2K_stage_input(rfm.RunOnlyRegressionTest):
  File "/data/brussel/100/vsc10009/reframe/eessitestsuite/test-suite/eessi/testsuite/tests/apps/cp2k/cp2k_staging/cp2k_stage_input.py", line 22, in EESSI_CP2K_stage_input
    sanity_patterns = sn.all([
  File "/data/brussel/100/vsc10009/reframe/eessitestsuite/test-suite/eessi/testsuite/tests/apps/cp2k/cp2k_staging/cp2k_stage_input.py", line 23, in <listcomp>
    sn.assert_found('.*', input_file, msg % input_file) for input_file in input_file_list
NameError: name 'msg' is not defined

a good explanation for the error is here:
https://stackoverflow.com/a/13913933

[smoors]

lgtm