Simple python-based script to run unit tests

[jllanfranchi]

Search through PISA codebase (from PISA/pisa/ dir) looking for *.py filenames. Within each *.py file, find functions defined by def test_*.

• Import each module quietly. If failure, re-import with trace-level output then print the original exception
• Run each test_* function. If there is an exception, re-run with trace-level verbosity. Also print the traceback.
• Print summary of numbers of modules loaded successfully / unsuccessfully and tests run successfully / unsuccessfully at the end
• Raise an exception / fail in the end of the script if any module failed to import or any test function raised an exception

Note that this takes ~1:20 to run on my PC (albeit there are no test pipelines being run and no hypo testing is being run)