Initial mesh_shaders sample commit

samples/mesh_shaders/shaders/mesh_triangle.vert

@@ -0,0 +1,12 @@
+#version 450
+#pragma shader_stage(vertex)
+
+#extension GL_EXT_descriptor_heap: require
+
+layout(descriptor_heap) uniform data {
+  vec4 positions[3];
+} vertexData[];
+
+void main() {
+  gl_Position = vertexData[0].positions[gl_VertexIndex];
+}