Move KeyboardBacklightListener to InputManagerGlobal

Move KeyboardBacklightListener, along with its associated
functions from InputManager to InputManagerGlobal.
Associated CLs for this refactoring:
- ag/21609952
- ag/21699437
- ag/21849880
- ag/21853350

Bug: b/267758905
Test: Pre-submit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:8a7eb1b26875cd45a656bbb8c925adddc4345e39)
Merged-In: I8f189a3c4aa1746ce9c225a19925a78375ec88b2

Change-Id: I69c31a5e5a64a8b36a584892007c0f943af0e375