Do not store .cpp/.h files inside src/main/java - mapbuffer

Summary:
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 mapbuffer

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

Reviewed By: cipolleschi

Differential Revision: D38699253

fbshipit-source-id: c1c8f8693b6da4e3428f8f280e1ca4d5c5d0f853

ReactAndroid/src/main/java/com/facebook/react/common/mapbuffer/BUCK

@@ -22,7 +22,7 @@ rn_android_library(
     deps = [
         FBJNI_TARGET,
         react_native_dep("libraries/soloader/java/com/facebook/soloader:soloader"),
-        react_native_target("java/com/facebook/react/common/mapbuffer/jni:jni"),
+        react_native_target("jni/react/mapbuffer:jni"),
         react_native_dep("libraries/fbjni:java"),
         react_native_dep("third-party/android/androidx:annotation"),
         react_native_dep("third-party/java/infer-annotations:infer-annotations"),

ReactAndroid/src/main/java/com/facebook/react/common/mapbuffer/ReadableMapBuffer.kt

@@ -17,7 +17,7 @@ import javax.annotation.concurrent.NotThreadSafe
 
 /**
  * Read-only implementation of the [MapBuffer], imported from C++ environment. Use
- * `<react/common/mapbuffer/jni/JReadableMapBuffer.h> to create it.
+ * `<react/common/mapbuffer/JReadableMapBuffer.h> to create it.
  *
  * See [MapBuffer] documentation for more details
  */

ReactAndroid/src/main/jni/CMakeLists.txt

@@ -98,7 +98,7 @@ add_react_android_subdir(src/main/jni/react/reactperflogger)
 add_react_android_subdir(src/main/jni/react/jscexecutor)
 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/java/com/facebook/react/common/mapbuffer/jni)
+add_react_android_subdir(src/main/jni/react/mapbuffer)
 add_react_android_subdir(src/main/java/com/facebook/react/fabric/jni)
 add_react_android_subdir(src/main/java/com/facebook/react/modules/blob/jni)
 add_react_android_subdir(src/main/jni/react/hermes/reactexecutor)

ReactCommon/react/utils/BUCK

@@ -36,7 +36,7 @@ rn_xplat_cxx_library(
     ),
     compiler_flags_pedantic = True,
     fbandroid_deps = [
-        react_native_target("java/com/facebook/react/common/mapbuffer/jni:jni"),
+        react_native_target("jni/react/mapbuffer:jni"),
         react_native_xplat_target("react/renderer/mapbuffer:mapbuffer"),
     ],
     fbobjc_compiler_flags = APPLE_COMPILER_FLAGS,