Added support for a DeviceConfig flag to dynamically switch between old

and new DPC

We now support dynamic switching between the old and the new DPCs such that it can be controlled remotely as well.
To use new DPC, run adb shell device_config put display_manager use_newly_structured_display_power_controller true
To use old DPC, run adb shell device_config put display_manager
use_newly_structured_display_power_controller false.
To check the current value, run adb shell device_config list | grep
"use_newly_structured_display_power_controller".
By default, we fallback to the old DPC

Test: Manual
Bug: 254004456
Change-Id: Ica0405bc6ec0b2cb7dd1f32a5ea618a8e506f2f7