Extract strictly augmented Hasse graph expansion out of TopoTune's train

[ninamiolane]

The mechanism of TopoTune that expands a topological domain into a set of strictly augmented Hasse graphs is very useful. However, it is hardly usable at the moment since it's hidden in the training process.

We need to extract it out so that it can be easily used by everyone, and so that it also speeds up training times in TopoTune.