Refactor codestyle and structure

[rmnigm]

Refactoring the source files.

• Code style fixes
• Added basic type hints, fixed linter checks
• Added ruff linter checks to CI/CD
• Removed local library torch.device, hardcoded to use GPU when possible, to user-set torch.device

[hushchyn-mikhail]

@rmnigm, hi!

Thank you for your PR. All your code changes look great! But when I run tests, they fail with the following error:

I did the following steps to reproduce it:

pip install -e .
pytest tests