Add a Constraint Programming Workload

[kylebd99]

Now, this one is a little tricky because CSP problems often also include numeric constraints. However, I believe that we can likely model these constraints through the use of additional factors depending on the problem. Alternatively, we can often model them using element-wise functions. The question then becomes whether those functions are associative/commutative/etc., and how we fit them into our framework.

Anyways, there's likely at least something basic here, but there might also be something more interesting.