Parallelize exportation of workflow SVGs

[cjsha]

I appreciate the ability to automatically export SVGs from workflows for building docs site. However, for people building docs on slower machines, the SVG exportation process can become quite lengthy. I don't think there's any reason this for loop needs to run in sequential order. I gave parallelization implementation a small attempt, but I don't seem to immediately know enough about powershell scripting to do it in a timely manner. If there is someone that can do this, that would be immensely helpful. Thanks.