feat: introduce the decodeFilter function to refactor filter parsing

[EshaanAgg]

Fixes #731 by creating a decodeFilter function, which splits the filterID passed to it and returns an object containing all the parts. Refactors all the previous usages of the old .split("_") approach as well to make use of this new helper function.

[PhilippWendler]

Thank you very much! I like a lot that you also thought of and added documentation, error handling, and unit tests nicely! 👍 This is fine to merge.

I am just wondering whether you maybe see more potential for refactorings in a similar way, i.e., by identifying duplicate (or just complex pieces of) code and moving them out into functions that can be individually documented tested?

[EshaanAgg]

Thanks for the review! I'll surely open issues regarding possible refactorings if I come across them in my exploration of the codebase!