Fabric: Setting mountingOverrideDelegate for MountingCoordinator directly

Summary:
Before this change, `mountingOverrideDelegate` was proxied via `Scheduler::startSurface` and `ShadowTree::ShadowTree` constructor down to `MountingCordinator`. Now we set it on the `MountingCoordinator` directly.

Changelog: [Internal] Fabric-specific internal change.

Reviewed By: sammy-SC

Differential Revision: D26049076

fbshipit-source-id: 7f1ecf2c8b6f264a7e59d19881464fe529c53d30

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp

@@ -255,7 +255,9 @@ void Binding::startSurface(
       moduleName->toStdString(),
       initialProps->consume(),
       {},
-      context,
+      context);
+
+  scheduler->findMountingCoordinator(surfaceId)->setMountingOverrideDelegate(
       animationDriver_);
 }
 
@@ -306,7 +308,9 @@ void Binding::startSurfaceWithConstraints(
       moduleName->toStdString(),
       initialProps->consume(),
       constraints,
-      context,
+      context);
+
+  scheduler->findMountingCoordinator(surfaceId)->setMountingOverrideDelegate(
       animationDriver_);
 }