Add scheduling for creating scheduled UWDs

[jpfairbanks]

NestedUWDs was moved to https://github.com/AlgebraicJulia/CategoricalTensorNetworks.jl. These ScheduledUWDs can be created with the Junction Tree Algorithms in this package. We should support a package extension for creating them.

[samuelsonric]

This is done. I will submit a patch to CategoricalTensorNetworks once we complete our first release.