Add goodness-of-fit tests

[vnmabus]

Energy distance can be used to perform goodness-of-fit tests, as mentioned in https://doi.org/10.1016/j.jspi.2013.03.018 (https://pages.stat.wisc.edu/~wahba/stat860public/pdf4/Energy/JSPI5102.pdf).

It would be useful to create a new submodule goodness that could include some of the following:

• Two-parameter exponential distribution goodness-of-fit test.
• Uniform distribution goodness-of-fit test.
• Univariate normality goodness-of-fit test.
• Multivariate normality goodness-of-fit test.
• Pareto distribution goodness-of-fit test.
• Poisson distribution goodness-of-fit test.
• Uniform distribution goodness-of-fit test.
• Stable distributions goodness-of-fit test.