Add Vulkan support for Mac (via MoltenVK)

Source/Engine/Graphics/GPUAdapter.h

@@ -9,6 +9,7 @@
 #define GPU_VENDOR_ID_INTEL 0x8086
 #define GPU_VENDOR_ID_NVIDIA 0x10DE
 #define GPU_VENDOR_ID_MICROSOFT 0x1414
+#define GPU_VENDOR_ID_APPLE 0x106B
 
 /// <summary>
 /// Interface for GPU device adapter.

Source/Engine/Graphics/Graphics.Build.cs

@@ -82,7 +82,8 @@ public class Graphics : EngineModule
             options.PrivateDependencies.Add("GraphicsDeviceVulkan");
             break;
         case TargetPlatform.Mac:
-            options.PrivateDependencies.Add("GraphicsDeviceNull"); // TODO: Graphics support on Mac
+            options.PrivateDependencies.Add("GraphicsDeviceNull");
+            options.PrivateDependencies.Add("GraphicsDeviceVulkan");
             break;
         default: throw new InvalidPlatformException(options.Platform.Target);
         }

Source/Engine/Graphics/Shaders/Cache/ShaderCacheManager.cpp

@@ -14,7 +14,7 @@
 const Char* ShaderProfileCacheDirNames[] =
 {
     // @formatter:off
-    TEXT("EARTH_IS_NOT_FLAT_XD"), // Unknown
+    TEXT(""), // Unknown
     TEXT("DX_SM4"), // DirectX_SM4
     TEXT("DX_SM5"), // DirectX_SM5
     TEXT("GLSL_410"), // GLSL_410