Reorganized folders for chunks and their collections

[mvaligursky]

folders before

shader-lib/
├── chunks-glsl/
├── chunks-wgsl/
└── collections/  (mixed)

folders now

shader-lib/
├── glsl/
│   ├── chunks/
│   └── collections/
└── wgsl/
    ├── chunks/
    └── collections/