Add vk_ray_trace_indirect_scissor sample

ray_tracing_indirect_scissor/shaders/LanternIndirectEntry.glsl

@@ -0,0 +1,18 @@
+struct LanternIndirectEntry
+{
+  // VkTraceRaysIndirectCommandKHR
+  int indirectWidth;
+  int indirectHeight;
+  int indirectDepth;
+
+  // Pixel coordinate of scissor rect upper-left.
+  int offsetX;
+  int offsetY;
+
+  // Lantern starts here:
+  // Can't use vec3 due to alignment.
+  float x, y, z;
+  float red, green, blue;
+  float brightness;
+  float radius;
+};