Make it easier for user to toggle only Fabric or TurboModules in New Architecture (#35091)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/35091

This diff refines the DefaultNewArchitectureEntryPoint to make it easier for user to
either turn on Fabric, TurboModules or both.

Changelog:
[Internal] [Changed] - Make it easier for user to toggle only Fabric or TurboModules in New Architecture

Reviewed By: cipolleschi

Differential Revision: D40710596

fbshipit-source-id: 236060b2ebccb1bf25e7f5c0fc15f54c5ce5f608

ReactAndroid/src/main/java/com/facebook/react/defaults/DefaultComponentsRegistry.kt

@@ -15,8 +15,8 @@ import com.facebook.react.fabric.ComponentFactory
  * A utility class that provides users a ComponentRegistry they can customize with a C++
  * implementation of its native methods.
  *
- * This class works together with the [DefaultNativeEntryPoint] and it's C++ implementation is
- * hosted inside the React Native framework
+ * This class works together with the [DefaultNewArchitectureEntryPoint] and it's C++ implementation
+ * is hosted inside the React Native framework
  */
 @DoNotStrip
 class DefaultComponentsRegistry

ReactAndroid/src/main/java/com/facebook/react/defaults/DefaultNativeEntryPoint.kt

@@ -1,29 +0,0 @@
-/*
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-package com.facebook.react.defaults
-
-import com.facebook.soloader.SoLoader
-
-/**
- * A utility class that serves as an entry point for users to register all the custom Fabric
- * Components and Turbo Native Modules.
- *
- * This class needs to be invoked as `DefaultNativeEntryPoint.load("...")` by passing the name of
- * the dynamic library to load.
- *
- * By default it loads a library called `appmodules`. `appmodules` is a convention used to refer to
- * the application dynamic library. If changed here should be updated also inside the template.
- */
-object DefaultNativeEntryPoint {
-  @JvmStatic
-  @JvmOverloads
-  fun load(dynamicLibraryName: String = "appmodules") {
-    SoLoader.loadLibrary("react_newarchdefaults")
-    SoLoader.loadLibrary(dynamicLibraryName)
-  }
-}

ReactAndroid/src/main/java/com/facebook/react/defaults/DefaultNewArchitectureEntryPoint.kt

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.defaults
+
+import com.facebook.react.config.ReactFeatureFlags
+import com.facebook.soloader.SoLoader
+
+/**
+ * A utility class that serves as an entry point for users setup the New Architecture.
+ *
+ * This class needs to be invoked as `DefaultNewArchitectureEntryPoint.load(...)` by passing a
+ * series of optional parameters.
+ *
+ * By default it loads a library called `appmodules`. `appmodules` is a convention used to refer to
+ * the application dynamic library. If changed here should be updated also inside the template.
+ *
+ * By default it also enables both TurboModules, Fabric and Concurrent React (aka React 18)
+ */
+object DefaultNewArchitectureEntryPoint {
+  @JvmStatic
+  @JvmOverloads
+  fun load(
+      dynamicLibraryName: String = "appmodules",
+      turboModulesEnabled: Boolean = true,
+      fabricEnabled: Boolean = true,
+      concurrentReactEnabled: Boolean = true
+  ) {
+    ReactFeatureFlags.useTurboModules = turboModulesEnabled
+    ReactFeatureFlags.enableFabricRenderer = fabricEnabled
+
+    this.fabricEnabled = fabricEnabled
+    this.turboModulesEnabled = turboModulesEnabled
+    this.concurrentReactEnabled = concurrentReactEnabled
+
+    SoLoader.loadLibrary("react_newarchdefaults")
+    SoLoader.loadLibrary(dynamicLibraryName)
+  }
+
+  @JvmStatic var fabricEnabled: Boolean = false
+
+  @JvmStatic var turboModulesEnabled: Boolean = false
+
+  @JvmStatic var concurrentReactEnabled: Boolean = false
+}

ReactAndroid/src/main/java/com/facebook/react/defaults/DefaultTurboModuleManagerDelegate.kt

@@ -17,8 +17,8 @@ import com.facebook.react.bridge.ReactApplicationContext
  * A utility class that allows you to simplify the setup of a
  * [ReactPackageTurboModuleManagerDelegate] for new apps in Open Source.
  *
- * This class works together with the [DefaultNativeEntryPoint] and it's C++ implementation is
- * hosted inside the React Native framework
+ * This class works together with the [DefaultNewArchitectureEntryPoint] and it's C++ implementation
+ * is hosted inside the React Native framework
  */
 class DefaultTurboModuleManagerDelegate
 private constructor(context: ReactApplicationContext, packages: List<ReactPackage>) :