Per-display WM brightness override.

The brightness overrides are keyed by displayId and passed
directly through DisplayManager to the relevant
OverrideBrightnessStrategy. Keeping the global brightness override
in PowerManager because it's used during boot.

Fix: 288052251
Test: atest
Flag: EXEMPT bugfix

Change-Id: Ic23970b9e7acd9f5edae04b27fe68f679c994d33
13 files changed