Add display config for configuring the idle state refresh rate timeout

bands

This is a step forward to attain the functionality where if the screen
is idle for a configurable time, we would want to switch the screen to
a lower refresh rate to preserve the battery

Bug: 310026579
Test: atest DisplayDeviceConfigTest
Change-Id: I92435cb355e0538171a07cc08c56bae561ab0ce4