Add ray traced glTF sample (#1083)

* Started working on a ray tracing glTF sample

* Started working on a ray tracing glTF sample

Added textures using descriptor indexing

* Frame accumulation

Pass glTF node transforms to BLAS build

* Shader cleanup

* Code cleanup, flip Y using TLAS transform matrix

* Create AS for all primitives in the gltf scene

* Remove unused variables

* Added missing shaders

* Minor cleanup

shaders/glsl/raytracinggltf/shadow.rmiss

@@ -0,0 +1,9 @@
+#version 460
+#extension GL_EXT_ray_tracing : require
+
+layout(location = 2) rayPayloadInEXT bool shadowed;
+
+void main()
+{
+	shadowed = false;
+}