Further simplify the New App Template by don't requiring the dynamic library name (#34671)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/34671

I'm simplifying the template further by:
- Do not expose a configurable dynamic library name. Let's use `appmodules`
and still allow the users to configure it, if needed.
- Move all the initialization logic inside the `JNI_OnLoad` method
- Cleanup the `DefaultReactNativeHost` to don't require a dynamic library
name but just a boolean.

Changelog:
[Android] [Changed] - Further simplify the New App Template by don't requiring the dynamic library name

Reviewed By: cipolleschi

Differential Revision: D39462948

fbshipit-source-id: 737733fc263162a0baf3b7a451e48b8616679d3b

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

@@ -16,7 +16,7 @@ import com.facebook.react.fabric.ComponentFactory
  * implementation of its native methods.
  *
  * This class works together with the [DefaultNativeEntryPoint] and it's C++ implementation is
- * hosted inside the React Native framwork
+ * hosted inside the React Native framework
  */
 @DoNotStrip
 class DefaultComponentsRegistry

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

@@ -7,8 +7,6 @@
 
 package com.facebook.react.defaults
 
-import com.facebook.jni.HybridData
-import com.facebook.proguard.annotations.DoNotStrip
 import com.facebook.soloader.SoLoader
 
 /**
@@ -18,22 +16,14 @@ import com.facebook.soloader.SoLoader
  * This class needs to be invoked as `DefaultNativeEntryPoint.load("...")` by passing the name of
  * the dynamic library to load.
  *
- * This class works together with the [DefaultNativeEntryPoint] and it's C++ implementation is
- * hosted inside the React Native framework
+ * 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.
  */
-@DoNotStrip
-class DefaultNativeEntryPoint @DoNotStrip private constructor() {
-
-  @DoNotStrip private val hybridData: HybridData = initHybrid()
-
-  @DoNotStrip private external fun initHybrid(): HybridData
-
-  companion object {
-    @JvmStatic
-    fun load(dynamicLibraryName: String) {
-      SoLoader.loadLibrary("react_newarchdefaults")
-      SoLoader.loadLibrary(dynamicLibraryName)
-      DefaultNativeEntryPoint()
-    }
+object DefaultNativeEntryPoint {
+  @JvmStatic
+  @JvmOverloads
+  fun load(dynamicLibraryName: String = "appmodules") {
+    SoLoader.loadLibrary("react_newarchdefaults")
+    SoLoader.loadLibrary(dynamicLibraryName)
   }
 }

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

@@ -25,29 +25,27 @@ abstract class DefaultReactNativeHost protected constructor(application: Applica
 
   override fun getReactPackageTurboModuleManagerDelegateBuilder():
       ReactPackageTurboModuleManagerDelegate.Builder? =
-      dynamicLibraryName?.let {
-        // If the user provided a dynamic library name, we assume they want to load
-        // the default ReactPackageTurboModuleManagerDelegate
+      if (isNewArchEnabled) {
         DefaultTurboModuleManagerDelegate.Builder()
+      } else {
+        null
       }
 
   override fun getJSIModulePackage(): JSIModulePackage? =
-      dynamicLibraryName?.let {
-        // If the user provided a dynamic library name, we assume they want to load
-        // the default JSIModulePackage
+      if (isNewArchEnabled) {
         DefaultJSIModulePackage(this)
+      } else {
+        null
       }
 
   /**
-   * Returns the name of the dynamic library used by app on the New Architecture. This is generally
-   * "<applicationname>_appmodules" or just "appmodules"
+   * Returns whether the user wants to use the New Architecture or not.
    *
-   * If null, we will assume you're not using the New Architecture and will not attempt to load any
-   * dynamic library at runtime.
+   * If true, we will load the default JSI Module Package and TurboModuleManagerDelegate needed to
+   * enable the New Architecture
    *
-   * If set, we'll take care of create a TurboModuleManagerDelegate that will load the library you
-   * specified.
+   * If false, the app will not attempt to load the New Architecture modules.
    */
-  protected open val dynamicLibraryName: String?
-    get() = null
+  protected open val isNewArchEnabled: Boolean
+    get() = false
 }

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

@@ -18,7 +18,7 @@ import com.facebook.react.bridge.ReactApplicationContext
  * [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 framwork
+ * hosted inside the React Native framework
  */
 class DefaultTurboModuleManagerDelegate
 private constructor(context: ReactApplicationContext, packages: List<ReactPackage>) :