Resolve "Implement a progress bar"

.gitignore

.pre-commit-config.yaml

README.md

src/flexi_splitter/flexi_splitter.py

src/flexi_splitter/suffix_tree.py

src/flexi_splitter/tests/__init__.py

src/flexi_splitter/tests/flexi_splitter_test.py

src/flexi_splitter/utils/__init__.py

src/setup.py