[IMG131] restructure the test folder
- Original Gitlab Task: IMG131
This PR introduces the following changes:
- move all previous tests into
tests/legacy
- setup the skeleton structure of the tests folder
- install pre-commit
- flake8 check is skipped as the current iMars3D source are not passing flake8 check
- removed nested .gitignore file
- use
2to3
to update some outdated test files