Add Pascals Triangle Test Generator

[jpreese]

This issue is part of an overall initiative to complete #195.

The documentation on how to add generators can be found here. If you get stuck or have any questions about adding this generator, please do not hesitate to reach out!

[bmeverett]

I'll take a look at this one as well. I think I got most of it, just trying to figure out the last two cases that are null and return -1

[ErikSchierboom]

@bmeverett Those inputs should throw an exception. To get that behavior in a generator, checkout this code: https://github.com/exercism/csharp/blob/9e4635b7dfc304c3985795054398d0a6402a9941/generators/Exercises/NthPrime.cs