Gaussian Splatting Updates

- [x] Ortho projection : https://github.com/BabylonJS/Babylon.js/pull/17307
- [x] Shadows https://github.com/BabylonJS/Babylon.js/pull/17316
- [x] Evaluate/test https://blog.playcanvas.com/playcanvas-adopts-sogs-for-20x-3dgs-compression https://github.com/BabylonJS/Babylon.js/pull/17212
- [x] Triangle Splatting for Real-Time Radiance Field Rendering https://trianglesplatting.github.io/
- [x] Arc rotate and camera limits https://github.com/BabylonJS/Babylon.js/pull/17492
- [x] Multiview/multicamera support https://github.com/BabylonJS/Babylon.js/pull/17508
- [x] Simplify math/remove hacks https://github.com/BabylonJS/Babylon.js/pull/17544
- [x] Rig/compound parts https://github.com/BabylonJS/Babylon.js/pull/17679
- [x] Bake Transforms https://github.com/BabylonJS/Babylon.js/pull/17840
- [x] GPU picker https://github.com/BabylonJS/Babylon.js/pull/17887
- [x] Material plugin-like for shader injection https://github.com/BabylonJS/Babylon.js/pull/17880
- [x] .babylon serialization https://github.com/BabylonJS/Babylon.js/pull/18032
- [ ] 4th order spherical harmonics https://github.com/BabylonJS/Babylon.js/pull/18459
- [x] WASM SPZ loader
- [ ] bone and bone weight support
- [ ] GS LOD https://forum.babylonjs.com/t/new-feature-niantic-spz-gaussian-splatting-and-spherical-harmonics/55124/24?u=cedric
- [x] Improve IsReady/Async with webworker: make sure instances are ready before `IsReady` is true.
- [ ] Use VRAM for storage instead of RAM
- [ ] optional sorting using Compute Shader

Note:
* splat conversion tool : https://github.com/playcanvas/splat-transform