Seperate our custom implementations from the originally forked

[moCello]

Summary

Currently the original implementation and our additions are intertwined all across the crate. We want to get an overview on the differences (and similarities) between our fork and the original. For this to happen we need a clear separation between the two.

Possible solution design or implementation

Possible add a module in each existing module that extends the original functionalities with our custom ones.

Additional context

Similar efforts are happening on our jubjub implementation, see jubjub issue