feat: 4d gaussians

[mosure]

what does this PR do?

features

• particle behavior - (1M+ particle updates)
• streamed wavelet behavior

refactor

• separate existing monoliths (core, sort, morph pipelines)

[mosure]

waiting on some of the following to be published before working on streamed wavelets. this effort will require synchronization with burn_gaussian_splatting project. more planning is required for optimal 4D representation (both streamed real-time and offline recreation, e.g. results from https://github.com/masked-spacetime-hashing/msth are promising)

• https://zielon.github.io/d3ga/
• https://xpandora.github.io/PhysGaussian/
• https://animatable-gaussians.github.io/
• https://imagine.enpc.fr/~guedona/sugar/