Unbundling

This is a first attempt, mostly for feedback for a dual bundled / unbundled testing workflow.

We always enable `useBundles`, then run unbundling prior to tests, unless running the `test:bundle` test, which ensures bundling is run.

Feedback welcome if this is the right approach or not.
I think I'd like unbundle to be in the `build` steps instead. @trentgrover-wf what do you think?