Settings: add a new developer menu entry to show hdr/sdr ratio overlay.

- The hdr/sdr ratio overlay will be shown on screen if the option is
  selected from the developer option.
- This option is hidden on non-HDR-supported devices.
- Add flags: com.android.settings.flags.development_hdr_sdr_ratio

Test: enable show hdr/sdr ratio from developer menu; com.android.settings.development.ShowHdrSdrRatioPreferenceControllerTest
Bug: 291863102
Change-Id: Idd72f95c67c95cd8127f9b94e031b3d87b18e307

src/com/android/settings/development/DevelopmentSettingsDashboardFragment.java

@@ -666,6 +666,7 @@ public class DevelopmentSettingsDashboardFragment extends RestrictedDashboardFra
         controllers.add(new ShowKeyPressesPreferenceController(context));
         controllers.add(new ShowSurfaceUpdatesPreferenceController(context));
         controllers.add(new ShowLayoutBoundsPreferenceController(context));
+        controllers.add(new ShowHdrSdrRatioPreferenceController(context));
         controllers.add(new ShowRefreshRatePreferenceController(context));
         controllers.add(new RtlLayoutPreferenceController(context));
         controllers.add(new WindowAnimationScalePreferenceController(context));