add ability to skip resource cleanup step

[jonfuller]

This change gives the user the option to skip the cleanup step at the end.

It creates a new parameter cleanupResources, which allows the cleanup of deleted resources to be skipped during the post-deployment phase. It defaults to true, and is optional to preserve current behavior.

While valuable, I ran into trouble using it because my pipeline names are parameterized in my template. This made it so the post-deployment cleanup phase always wants to delete my new pipelines, because it is doing a naive name comparison, not the "evaluated" name of my pipeline. Which, makes sense, and would be a MUCH harder problem to solve.