Reduce visibility of ReactHost.prerenderSurface (facebook#38699)

Summary:
Pull Request resolved: facebook#38699

Reduce visibility of ReactHost.prerenderSurface since this is only used from ReactSurface

changelog: [internal] internal

Reviewed By: christophpurrer

Differential Revision: D47915588

fbshipit-source-id: 953b04b531d718434170d63e9f66d22758d26ddf

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridgeless/ReactHost.java

@@ -200,7 +200,7 @@ public TaskInterface<Void> start() {
   }
 
   /** Initialize and run a React Native surface in a background without mounting real views. */
-  public Task<Void> prerenderSurface(final ReactSurface surface) {
+  /* package */ Task<Void> prerenderSurface(final ReactSurface surface) {
     final String method = "prerenderSurface(surfaceId = " + surface.getSurfaceID() + ")";
     log(method, "Schedule");