Find a range of possible outcomes where the cdf evaluates to values
that encapsulate the range of probabilities contained in the vector
encapsulate_p(distribution, p, direction)
A distribution having access to a cdf.
Vector of values between 0 and 1 (inclusive).
"left" for calculating left-inverse, or
"right" for calculating right-inverse.
If 0 or 1 are included in the vector
p, one of the endpoints might