[Fixes #70508876] Namespacing for unit tests

So that our tests aren't extending and implicitly namespaced into the
`Vcloud` module. This will make it more obvious where we're crossing the
boundaries of different projects. It will also instantiate the class given
(without any args) and make it available as `subject` which may allow us to
DRY up some of our tests.

---

It's possible to define a subject for `VappOrchestrator` which makes the tests shorter but I'm undecided if they are more readable - https://gist.github.com/dcarley/a9b8d03ce6a8a29727d3