Move test input/output to separate directories

[jesper-friis]

Currently running the tests pollutes the current directory with a lot of test output files. To avoid this, write test output to a output sub-directory of the test directory.

It would also be easier to spot test input if they are moved to a input sub-directory of the test directory.

Test directories that should be fixed:

• [ ] bindings/python/tests/
• [ ] bindings/fortran/tests/
• [ ] src/tests/
• [ ] src/utils/tests/
• [ ] storages/json/tests/
• [ ] storages/rdf/tests/
• [ ] tools/tests/

[jesper-friis]

PR #720 addresses this for two tests in binding/python/tests/