Simplify attribute editing

[Pyrofab]

Currently, when using the config builder, client applications have to manually add every attribute and give it the right type.

We should offer third-party libraries an easy and type-safe way to setup their attributes. This is already possible for POJO configs thanks to annotation processors, and could easily be added to builders by adding a method that takes a list of attributes, which could itself be created by a third party builder.