Rename and relocate scripts into modules

doc/api.rst

doc/references.rst

src/ptbench/data/datamodule.py

src/ptbench/engine/road_calculator.py

src/ptbench/engine/saliency/__init__.py

src/ptbench/engine/saliency/completeness.py

src/ptbench/engine/saliency/generator.py

src/ptbench/engine/saliency/interpretability.py

src/ptbench/scripts/calculate_road.py

src/ptbench/scripts/cli.py

src/ptbench/scripts/generate_saliencymaps.py

src/ptbench/scripts/saliency_completeness.py

src/ptbench/scripts/saliency_interpretability.py