Refactor Soft Delete Specs

Just for more discussion

This one was much harder. There's a few inline comments I want to make for discussion, but I'd also like input on what's left in https://github.com/OregonDigital/oregondigital/blob/feature/TrySoftDeleteSpecs/spec/features/soft_delete_spec.rb , which is primarily "display things that are queried". Any thoughts on how to pull that out? Or is this just the only way to avoid mucking about in Blacklight stuff?
Neat protip, you don't have to provide the full path to the key. Try `destroyed.undelete.success`, I believe you'll find that you don't need to be any more specific than is absolutely required. It's nice for when you've got a lot of internationalization and the path gets long.