Fix building Android on Windows (#39190)

Summary:
Currently Android fails to build on Windows, because CMake cannot work with
native Windows paths that are passed to it as build arguments. This change
converts the input paths to the CMake format.

## Changelog:

[Android] [Fixed] - Fix building Android on Windows.

Pull Request resolved: #39190

Test Plan: Build the React Native Android project on Windows. It should complete successfully.

Reviewed By: NickGerleman

Differential Revision: D48948140

Pulled By: cortinico

fbshipit-source-id: 6d584c2a10e683cdb6df0dd6dcd5875da7e06e2b

packages/react-native/ReactAndroid/src/main/jni/CMakeLists.txt

@@ -8,6 +8,11 @@ set(CMAKE_VERBOSE_MAKEFILE on)
 
 project(ReactAndroid)
 
+# Convert input paths to CMake format (with forward slashes)
+file(TO_CMAKE_PATH "${REACT_ANDROID_DIR}" REACT_ANDROID_DIR)
+file(TO_CMAKE_PATH "${REACT_BUILD_DIR}" REACT_BUILD_DIR)
+file(TO_CMAKE_PATH "${REACT_COMMON_DIR}" REACT_COMMON_DIR)
+
 # If you have ccache installed, we're going to honor it.
 find_program(CCACHE_FOUND ccache)
 if(CCACHE_FOUND)