Final solution for `taxClassId` configuration

[rintisch]

Feature Request

Is your feature request related to a problem? Please describe. According to the changelog documentation https://docs.typo3.org/p/extcode/cart/main/en-us/Changelog/7.3/Feature-339-TaxationOfServiceCostAsAnAncillaryService.html (or if the link some when might be outdated see https://github.com/extcode/cart/commit/123b441741aa993ee721dcea8ac32d2cea4bb055#diff-6824b8d62c7724590e03ddb85fb20aee3537ad5eb787b15572798a7ca0250c83) the taxClassId configuration with negative values was only planned as temporary solution.

Describe the solution you'd like A final solution for the problem. This might also solve #425