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 UniformRandom (+something like randomly-sampled UniformMultiplicity) spectral sampling should also handle error_threshold check #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: #1651