Study and implement energy-based clustering

[vnmabus]

As mentioned in https://doi.org/10.1016/j.jspi.2013.03.018 (https://pages.stat.wisc.edu/~wahba/stat860public/pdf4/Energy/JSPI5102.pdf), the energy distance can be used to implement a linkage method for hierarchical clustering.

We should study the best way to implement it, if possible in a manner compatible with existing hierarchical clustering methods, such as scipy methods and scikit-learn AgglomerativeClustering class.