Update ray tracing samples to use VK_KHR_ray_tracing (#753)

* Started updating ray tracing samples to KHR extension

* Updated GLSL shaders to use GL_EXT_ray_tracing

* Code cleanup, naming

* Fix include directories to use Vulkan headers from repository instead of NDK for the Android build

* Added new Android function pointers

* Renamed basic ray tracing sample

Added android build files

* Remove unused batch file

* Replaced remaining NV identifiers

* Updating ray tracing shadow sample to KHR extension

* Updated shaders to use KHR instead of NV extension

Fixed shader bindings

* Updating ray tracing reflections sample to KHR extension

* Renamed ray tracing reflections sample

* Renamed ray tracing shadows sample

Added android build files

* Removed no-longer used batch files for shader generation

* Proper alignment for the shader binding table

* Updated readme

* Reworked shader group setup

* Cleanup

* Reworked shader group setup

* Reworked shader group setup

* Code cleanup

data/shaders/hlsl/raytracingbasic/miss.rmiss

@@ -0,0 +1,12 @@
+// Copyright 2020 Google LLC
+
+struct Payload
+{
+[[vk::location(0)]] float3 hitValue;
+};
+
+[shader("miss")]
+void main(inout Payload p)
+{
+    p.hitValue = float3(0.0, 0.0, 0.2);
+}