Added HLSL shaders for ray tracing callable sample

Minor cleanup

data/shaders/hlsl/raytracingcallable/miss.rmiss

@@ -0,0 +1,12 @@
+// Copyright 2021 Sascha Willems
+
+struct Payload
+{
+[[vk::location(0)]] float3 hitValue;
+};
+
+[shader("miss")]
+void main(inout Payload p)
+{
+    p.hitValue = float3(0.0, 0.0, 0.2);
+}