Add the phong shader to allow performant materials

[AdaRoseCannon]

Description:

Add the THREE.js Phong material to let developers use a more perfomant material for large non-flat objects.

Changes proposed:

• Fixes an issue in layers.js that was preventing it from being merged
• Fixes a bug in reflection.js where there was a circular texture dependency
• Phong material code based on standard material but tweaked for phong parameters
• Phong envMap defaults to a getter to the scene.environment because phong materials don't automatically use the scene.environment

[AdaRoseCannon]

This has the weird side effect of actually handling the environment maps from the lighting estimation API better than the standard material

[dmarcos]

Thank you!