Review Request for PR refactoring PBRLighting.frag

I recently made this PR Modularize PBRLighting.frag by yaRnMcDonuts · Pull Request #2191 · jMonkeyEngine/jmonkeyengine · GitHub which refactors PBRLighting to split the lighting into a .glsllib file and the texture reads/matParam reads into a seperate .glsllib file.

This will make it easier for shader devs to keep their own forks of PBRlighting up to date with the version on master. This PR also eliminates the chance of breaking the lighting code in the forking process, since the lighting code will be tucked away nicely in its own glsllib that will never need touched by most shader devs.

Can anyone take a look and let me know your thoughts?

I am hoping that this could make it into the next 3.7 release if possible, since it is not really a new feature and is just a bunch of refactoring, and should be fairly easy to test.