New Spectral Sampling Following Optimal Transport Scheme of Matsushima eet al., 2023

[emmacware]

• [ ] new file in https://github.com/open-atmos/PySDM/tree/main/PySDM/initialisation/sampling ?
• [ ] alpha parameter as ctor arg.
• [ ] unit tests with boundaries alpha=0, alpha=1 against existing methods uniform and constant multiplicity sampling
• [ ] exemplify both random and deterministic cases (random const. mult. not exemplified yet in PySDM!)
• [ ] resolve #1031
• [ ] new example: Fig 1 from Matsushima 2023
• [ ] smoke tests for the new example notebook
• [ ] use it in the adaptivity paper

[slayoo]

being addressed here: https://github.com/open-atmos/PySDM/pull/1651