Do not store .cpp/.h files inside src/main/java - fabricjni (facebook#34435)

Summary:
Pull Request resolved: facebook#34435

Currently we expose native code (.h, .cpp) inside the src/main/java folder.
This is making impossible for users on New Architecture to open the project
inside Android Studio.

The problem is that the src/main/java is reserved to Java/Kotlin sources only.
AGP 7.2 also removed support for mixed source roots:
https://developer.android.com/studio/releases/gradle-plugin#duplicate-content-roots

This is essentially forcing users to write Java code without any autocompletion
as all the React Native Java classes are considered C++ files.

I'm addressing this issue folder by folder by moving them
from ReactAndroid/src/main/java/com/facebook/... to ReactAndroid/src/main/jni/react/...

This is the diff for fabricjni

Changelog:
[Internal] [Changed] - Do not store .cpp/.h files inside src/main/java - fabricjni

Reviewed By: cipolleschi

Differential Revision: D38741130

fbshipit-source-id: f9e3e4514d3ae0ddeac65256928d71d5134d08f8

Author: cortinico

ReactAndroid/cmake-utils/Android-prebuilt.cmake

@@ -193,7 +193,7 @@ set_target_properties(fabricjni
         PROPERTIES
         IMPORTED_LOCATION
         ${REACT_NDK_EXPORT_DIR}/${ANDROID_ABI}/libfabricjni.so)
-target_include_directories(fabricjni INTERFACE ${REACT_ANDROID_SRC_DIR}/java/com/facebook/react/fabric/jni)
+target_include_directories(fabricjni INTERFACE ${REACT_ANDROID_SRC_DIR}/jni/react/fabric)
 
 ## react_render_componentregistry
 add_library(react_render_componentregistry SHARED IMPORTED GLOBAL)

ReactAndroid/src/main/java/com/facebook/react/fabric/BUCK

@@ -42,7 +42,6 @@ rn_android_library(
         react_native_target("java/com/facebook/debug/holder:holder"),
         react_native_target("java/com/facebook/react/bridge:bridge"),
         react_native_target("java/com/facebook/react/config:config"),
-        react_native_target("java/com/facebook/react/fabric/jni:jni"),
         react_native_target("java/com/facebook/react/module/annotations:annotations"),
         react_native_target("java/com/facebook/react/modules/core:core"),
         react_native_target("java/com/facebook/react/modules/i18nmanager:i18nmanager"),
@@ -52,5 +51,6 @@ rn_android_library(
         react_native_target("java/com/facebook/react/views/view:view"),
         react_native_target("java/com/facebook/react/views/text:text"),
         react_native_target("java/com/facebook/react/touch:touch"),
+        react_native_target("jni/react/fabric:jni"),
     ] + KOTLIN_STDLIB_DEPS,
 )

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

@@ -294,7 +294,7 @@ public <T extends View> int addRootView(
    * @return a {@link ReadableMap} that contains metadata associated to the React Component that
    *     rendered the Android View received as a parameter. For more details about the keys stored
    *     in the {@link ReadableMap} refer to the "getInspectorDataForInstance" method from
-   *     com/facebook/react/fabric/jni/Binding.cpp file.
+   *     jni/react/fabric/Binding.cpp file.
    */
   @UiThread
   @ThreadConfined(UI)

ReactAndroid/src/main/jni/CMakeLists.txt

@@ -100,7 +100,7 @@ add_react_android_subdir(src/main/java/com/facebook/react/turbomodule/core/jni)
 add_react_android_subdir(src/main/jni/react/uimanager)
 add_react_android_subdir(src/main/jni/react/mapbuffer)
 add_react_android_subdir(src/main/jni/react/reactnativeblob)
-add_react_android_subdir(src/main/java/com/facebook/react/fabric/jni)
+add_react_android_subdir(src/main/jni/react/fabric)
 add_react_android_subdir(src/main/jni/react/hermes/reactexecutor)
 add_react_android_subdir(src/main/jni/react/hermes/instrumentation/)