Replace "validate" functions with nan for distributions

[berkay-yalin]

Instead of raising exceptions within the "validate" functions when invalid arguments are used with the distribution functions, the nan value should be returned.

The reasoning behind this decision is to support large scale operations on arrays.

This makes identifying invalid arguments much more difficult, as the current "validate" functions provide detailed descriptions for why the arguments are rejected, so a more effective solution is welcome for discussion.

Example "validate" function, where each distribution function has its separate "validate" function:

promethium/src/promethium/distributions/binomial.py

Lines 6 to 18 in 668cc82

	def pmf_validate(x: Any, n: Any, p: Any) -> None:
	if not isinstance(x, int):
	raise TypeError("x must be a non-negative integer")
	if x < 0:
	raise ValueError("x value out of domain")
	if not isinstance(n, int):
	raise TypeError("n must be a non-negative integer")
	if n < 0:
	raise ValueError("n value out of domain")
	if not isinstance(p, float):
	raise TypeError("p must be non-negative float")
	if not 0 <= p <= 1:
	raise ValueError("p value out of domain")