MoltenVK Support for macOS is now open source

[AnyOldName3]

In the other threads that were made about this, it was mentioned that a native Metal backend was already being worked on. It might be a worthwhile effort to keep on trying MoltenVK, even if it only serves to provide the MoltenVK people with test cases, but it's not strictly necessary to do anything as a Metal backend will end up in master-branch Dolphin at some point.