Handle DISPLAY_EVENT_FRAME_RATE_OVERRIDE

When getting DISPLAY_EVENT_FRAME_RATE_OVERRIDE from SurfaceFlinger,
expose the overridden frame rate to the relevant application
if the current refresh rate allows that.

Bug: 169271059
Bug: 169271062
Bug: 170503758
Test: manual test using SF backdoor
adb shell service call SurfaceFlinger 1039 i32 <uid> f <refresh rate>

Change-Id: I6ae1a98e6ca13e9d3d095a5713a6b0ca99652256