Enable correct usage of dataclasses in preprocessing config

Summary

This MR introduces the following changes

• Moving the check_option_definition function (which is needed for the dataclasses) to the tools.
• Setup all the needed dataclasses and checkups for the configs
• Remove old "dirty" checkups of the configs
• A lot of renaming (from the dict form to the attribute form (["fractions"]->.fractions))
• Removing some old not-used custom_n_jets_initial code
• Adapting all unit/integration tests accordingly

Relates to the following issues

• Closes #232 (closed)

Conformity

• Changelog entry
• Documentation
• Development guidelines
• Style guides