[Task] Check if parameters of `Partioning` should be optimizable

[SCiarella]

As pointed out in this comment we can check if the parameters of Partitioning can and should be optimized.
If that is the case, we should also add a notebook to show the optimization, similar to other modules.

[SarahAlidoost]

See this pcse notebook / 11 Optimizing partitioning in a PCSE model.ipynb

[SarahAlidoost]

As discussed in our update meeting and shown in the notebook in #76, optimizing the parameters using the output of the module doesnot make sense. Because first we approximate partitioning variables using a sigmoid then the tables are passed to partitioning module involving a linear interpolation. Finally in the optimization we want to fit the output of a linear interpolation to the observation. This is conceptually wrong. The best approach is to replace the partitioning module with another approximation like sigmoid and then in optimization find the parameters of the sigmoid.