[Task]: Make `Partitioning` differentiable and efficient

The module [Partitioning](https://github.com/ajwdewit/pcse/blob/master/pcse/crop/partitioning.py) has two classes: `DVS_Partitioning` and `DVS_Partitioning_N`. Only `DVS_Partitioning` should be changed. The class `DVS_Partitioning_N` is used in `wofost81` and will be later implemented. See explanations and requirements in https://github.com/WUR-AI/diffWOFOST/issues/39.