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?
There's also https://github.com/OregonDigital/oregondigital/commit/955c7c5731e3dc4bc99a63aa6c817a77a481a8b2. It binds us to GenericAsset.find, but it does ensure that it gets called and set appropriately.