Notebook illustrating semi-values

#319 implements Banzhaf indices and Beta Shapley, but only superficially documents them. We need a notebook comparing them to other methods, along the lines of the experiments in the respective papers.

This should be done after or as part of #230 and #231

Look at the implementation of Banzhaf indices and Beta Shapley from issue #319. Review the papers referenced for these methods to understand the experimental comparisons needed. Create a Jupyter notebook in the repository's examples or docs section, following the style of existing notebooks. The notebook should compare these methods to other data valuation techniques already in pyDVL, demonstrating their behavior and utility.

Written by the indexing model from the issue text.