[VK] Add Vulkan backend CI testing on KosmicKrisp

[KosmicKrisp](https://docs.mesa3d.org/drivers/kosmickrisp.html) is the Mesa Vulkan-on-Metal implementation. Currently [MoltenVK](https://github.com/KhronosGroup/MoltenVK/) is used to test the AdaptiveCpp Vulkan backend on MacOS, but KosmicKrisp is gaining traction as the preferred Vulkan-on-Metal implementation, and so it would be good to test it out.