Support non-wizard mode

[main--]

Scenario A: Using windows-gaming within some scripted thing (unlikely but possible).

Scenario B: You'd like to do something the wizard doesn't directly support, e.g. slightly modifying my setup later without starting over entirely.

The original design intended for you to just edit the config, but TOML is not that popular and it's not always enough (config files and stuff).

[oberien]

We aren't using toml anymore but yaml instead. But the issue that config files aren't enough to control everything is still the case.

Therefore we need to change of the whole setup which I already started:

• Split each step into its own module.
• Refactor each step independendly and make them more user-friendly.
• Introduce a command line argument parsing library like clap.
• Allow execution of all steps, a list of steps or a single step.