PlayStation Controller lightbar support

Celeste natively controls the lightbar color on PS controllers. However, there's no way to disable the lightbar without resorting to external tools like Steam. An option to toggle the lightbar could be added to Everest.
Additionally, vanilla changes the lightbar color on chapter select and level enter based on the TitleBaseColor for the chapter, but this only works for vanilla chapters. This behavior could be extended to custom maps fairly easily.