Added HLSL shaders for mesh shading sample

shaders/hlsl/meshshader/meshshader.task

@@ -0,0 +1,19 @@
+/* Copyright (c) 2023, Sascha Willems
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ */
+
+struct DummyPayLoad
+{ 
+    uint dummyData; 
+}; 
+
+// We don't use pay loads in this sample, but the fn call requires one
+groupshared DummyPayLoad dummyPayLoad;
+
+[numthreads(1,1,1)] 
+void main()
+{
+	DispatchMesh(3, 1, 1, dummyPayLoad);
+}