Introduce DefaultValuesReactNativeConfig constant

Summary:
Introduce DefaultValuesReactNativeConfig constant that represents a ReactNativeConfig that always return default values

I also use this constant in all the apps using fbaric that don't have a custom Mobile Config

changelog: [internal] internal

Reviewed By: RSNara

Differential Revision: D34160478

fbshipit-source-id: 5730054fd4cc87e1fe5dc8247cc237194bf48981

ReactAndroid/src/main/java/com/facebook/react/fabric/ReactNativeConfig.java

@@ -22,6 +22,30 @@ import com.facebook.proguard.annotations.DoNotStrip;
  */
 @DoNotStrip
 public interface ReactNativeConfig {
+
+  public final ReactNativeConfig DefaultValuesReactNativeConfig =
+      new ReactNativeConfig() {
+        @Override
+        public boolean getBool(@NonNull String param) {
+          return false;
+        }
+
+        @Override
+        public long getInt64(@NonNull String param) {
+          return 0;
+        }
+
+        @Override
+        public String getString(@NonNull String param) {
+          return null;
+        }
+
+        @Override
+        public double getDouble(@NonNull String param) {
+          return 0;
+        }
+      };
+
   /**
    * Get a boolean param by string name. Default should be false.
    *