Add some array/iterator functions to the stdlib

[jfecher]

Problem

Now that we have higher order functions we can support functions like map and fold for arrays which lessens the need for repetitive for loops.

Solution

Add these functions to the std::array module. Note that because we cannot dynamically grow arrays the only way to produce a new array of type [T; N] would be to take an existing element of the original array and replicate it N times, then mutate from there. This assumes the original array is of at least length 1. This should be a fine assumption currently as we assume all arrays are non-empty still.