Add support for .cube LUTs

Previous forum discussion: Support for .cube luts? - #2 by Julien1

Right now colorGradingTexture only supports .3dl file.

The problem is very simple: a lot of tools (e.g. Davinci Resolve) can only export .cube files. It’d be nice to have first class support for that format to avoid extra conversion. Also, after hours of searching, I found no open-source utility to convert between the two formats, so I’m not sure that such conversion is even available.

An example .cube loader can be found in the amazing postprocessing library: postprocessing/src/loaders/LUTCubeLoader.js at main · pmndrs/postprocessing · GitHub

Ported from GitHub