Add Unit Tests to Base Worker repo to avoid regressions

.gitignore

.gitlab-ci.yml

.isort.cfg

arkindex_worker/worker.py

tests-requirements.txt

tests/__init__.py

tests/conftest.py

tests/data/test_image.jpg

tests/data/tiled_image.jpg

tests/test_base_worker.py

tests/test_element.py

tests/test_elements_worker.py

tests/test_image.py

tests/test_reporting.py

tox.ini