Current `Serializer` is hard to maintain

[torkleyy]

The problem

The current serializer provides all kind of config parameters, but as it is now, it became hard to maintain. Many things are special cased, and code is duplicated across tuples / enums / sequences / maps.

Additionally, we're lacking tests for pretty serialization.

How to fix this

We need to build an abstraction for comma separated values, which removes the duplication we have now.

Once that's done, special cases should be easier to identify.

[github-actions[bot]]

Issue has had no activity in the last 180 days and is going to be closed in 7 days if no further activity occurs

[torkleyy]

This is still a problem, although we have more tests now thanks to @MomoLangenstein which should make refactoring easier.

[kvark]

weird that GH actions bot closes this, even thought there is a comment?

[juntyr]

I think that #206 fixed the code duplication issue and #488 finally pushed the serialising code to 100% code coverage