SF: Introduce DisplayModeController

DisplayModeController will centralize the logic and state for selecting
the DisplayMode of each physical display. For now, register a display's
DisplaySnapshot with DMC during configure, and move the creation of its
RefreshRateSelector to DMC::registerDisplay.

Bug: 241285876
Test: presubmit
Change-Id: I673914328bea64636b8bcd193e710131926334a5