Add new SF backdoor option: hdr/sdr ratio overlay

 - follow how RefreshRateOverlay did in general.
 - 1043 as new opcode to enable hdr/sdr ratio overlay.
 - decouple SevenSegmentDrawer and SurfaceControlHandle helper classes
   from RefreshRateOverlay.
 - add corresponding SF backdoor test for validation.
 - for non-HDR-supported device, we don't reject them to use SF backdoor
   but 1.00 will be always shown on the screen if enabling.

Test: adb shell call service call SurfaceFlinger 1043 1; atest
SurfaceFlinger_test
Bug: 277957056

Change-Id: Ifce2d435f127b53ab9d01aba4e24ffd4fdb010a7