Mark ReactNativeHost as deprecated In new architecture (#39765)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/39765

Mark ReactNativeHost as deprecated In new architecture

changelog: [internal] internal

bypass-github-export-checks

Reviewed By: cortinico

Differential Revision: D49834869

fbshipit-source-id: ab5b32068c130b6dd4f2511e4a0c0e3029e462ed

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

@@ -17,6 +17,7 @@ import com.facebook.react.bridge.ReactMarkerConstants;
 import com.facebook.react.common.LifecycleState;
 import com.facebook.react.common.SurfaceDelegate;
 import com.facebook.react.common.SurfaceDelegateFactory;
+import com.facebook.react.common.annotations.DeprecatedInNewArchitecture;
 import com.facebook.react.devsupport.DevSupportManagerFactory;
 import com.facebook.react.devsupport.interfaces.DevLoadingViewManager;
 import com.facebook.react.devsupport.interfaces.RedBoxHandler;
@@ -26,6 +27,9 @@ import java.util.List;
  * Simple class that holds an instance of {@link ReactInstanceManager}. This can be used in your
  * {@link Application class} (see {@link ReactApplication}), or as a static field.
  */
+@DeprecatedInNewArchitecture(
+    message =
+        "This class will be replaced by com.facebook.react.ReactHost in the new architecture of React Native.")
 public abstract class ReactNativeHost {
 
   private final Application mApplication;

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/annotations/DeprecatedInNewArchitecture.kt

@@ -13,4 +13,4 @@ package com.facebook.react.common.annotations
  */
 @Retention(AnnotationRetention.SOURCE)
 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
-annotation class DeprecatedInNewArchitecture
+annotation class DeprecatedInNewArchitecture(val message: String = "")