When running python interpreter directly, it may create __pycache__
sub-directories. Ignore those.

Signed-off-by: Shachar Sharon <ssharon@ibm.com>

Have top-level 'conftest.py' for pytest's fixtures [1], to allow sharing
fixtures across multiple files. Begin with an empty file and content as
needed.

[1] https://docs.pytest.org/en/7.4.x/reference/fixtures.html

Signed-off-by: Shachar Sharon <ssharon@ibm.com>

Use tox to run pytests with all its dependencies. In particular
configure tox to run pytest using pytest-randomly[1] to have better
control on random seed and allow reproducing tests seed.

Signed-off-by: Shachar Sharon <ssharon@ibm.com>

Prefer tox with all its glory over raw shell command. Use top-level
Makefile as an easy wrapper over tox. Assuming tox is already installed
on local-host/local-user.

Signed-off-by: Shachar Sharon <ssharon@ibm.com>