Move central options from taxonomies and select lists into (separate) module settings by callbacks

Problem/Motivation

Some option fields are currently implemented as taxonomy reference or List (Text) which makes them hard to maintain/update by config. Might be better to put the management of these into a setting (textarea or similar) which is used as source. Perhaps a list field also allows to use a function as values source?

In some cases like colors it might make sense to put them into a separate dedicated small module (not theme as we don't want that large dependency) to also make them centrally available for other modules.

In general our list_string fields shouldn't use the configuration to provide the values and instead better use callbacks, so we don't need update hooks to add new values and can also delegate this to a central settings page for example (if needed).

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes