VideoBackends:Vulkan: Use Vulkan 1.2 driverID to detect MoltenVK

Previously we'd assume all Apple GPUs were MoltenVK, including those running on Asahi Linux with open source Honeykrisp drivers.

Source/Core/VideoBackends/Vulkan/VulkanContext.h

@@ -39,6 +39,7 @@ public:
     float pointSizeRange[2];
     float maxSamplerAnisotropy;
     u32 subgroupSize = 1;
+    VkDriverId driverID = static_cast<VkDriverId>(0);
     bool dualSrcBlend;
     bool geometryShader;
     bool samplerAnisotropy;