refactor(contact_player.py): part1: basic refactoring, move functionality to main() function

[axodentally]

Move the main script logic into a new main() function.
Global variables move to local variables and get passed as function arguments, like the nodes dictionary.

Further really basic reformatting.

[axodentally]

This change is part of the following stack:

• refactor(contact_player.py): part1: basic refactoring, move functionality to main() function #20 ◀
  • refactor(contact_player.py): part2: improve type hints, add docstrings #21
    • refactor(contact_player.py): part3: Introduction of a new data model and addition of some level of abstraction #22
      • feat(contact_player): initial planned_contacts support #23
        • tests: add unittests #24
          • Introduce pyproject.toml, restructure installation #25

_{Change managed by git-spice.}

[axodentally]

I did not ask for a review of this github-code-quality bot... but dismissed all findings since they are all in the old code, that I did not even touch. This PR only moved old code around.

The refactoring is done in the other PRs.

Therefor none of the comments are relevant.