[orx-shader-phrases] Add shader embedding

orx-shader-phrases/src/shaders/glsl/phraseValueNoise21.shader

@@ -0,0 +1,14 @@
+#pragma import phraseHash21
+
+float valueNoise21(vec2 x) {
+    vec2 i = floor(x);
+    vec2 f = fract(x);
+
+    float a = hash21(i);
+    float b = hash21(i + vec2(1.0, 0.0));
+    float c = hash21(i + vec2(0.0, 1.0));
+    float d = hash21(i + vec2(1.0, 1.0));
+
+    vec2 u = f * f * (3.0 - 2.0 * f);
+    return mix(a, b, u.x) + (c - a) * u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
+}