Add Cubemap to Equirectangular example

Get 6 images (or skybox) then convert to Equirectangular (and maybe use Apache Commons Image to generate Facebook exifs).

Start by locating the example entry point for Cubemap and Equirectangular conversion, then review how examples in this repository handle image inputs. Define the result using six images or a skybox, and determine whether Apache Commons Image is needed for Facebook EXIF generation. Done means the example performs the conversion and produces the expected Equirectangular output.

Written by the indexing model from the issue text.