Add GLSL implementation of fractal noise for p5.strands

- Created src/webgl/shaders/functions/noise.glsl.js
- Provides a simple fractal noise function using 3 octaves

Author: LalitNarayanYadav

src/webgl/shaders/functions/noise.glsl.js

@@ -0,0 +1,15 @@
+export default /* glsl */ `
+float baseNoise(vec2 st) {
+  return fract(sin(dot(st.xy ,vec2(12.9898,78.233))) * 43758.5453123);
+}
+
+float noise(vec2 st) {
+  float result = 0.0;
+  for (int i = 0; i < 3; i++) {
+    float freq = pow(2.0, float(i));
+    float amp = pow(0.5, float(i));
+    result += amp * baseNoise(st * freq);
+  }
+  return result;
+}
+`;