SurfaceFlinger: add a backdoor to override display config

To generate a config change (and override all other config changes):
    adb shell service call SurfaceFlinger 1035 i32 <config_id>
To disable backdoor override:
    adb shell service call SurfaceFlinger 1035 i32 -1

Test: change configs from backdoor
Fixes: 130044117
Change-Id: Iab5a4ca4866139946ca3f8a6ac78fa9e13fe6d00
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index d8108c5..056c5f2 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -1148,6 +1148,9 @@
     Hwc2::impl::PowerAdvisor mPowerAdvisor;
 
     std::unique_ptr<RefreshRateOverlay> mRefreshRateOverlay;
+
+    // Flag used to set override allowed display configs from backdoor
+    bool mDebugDisplayConfigSetByBackdoor = false;
 };
 
 } // namespace android