Add Xcode build script for macOS target (#31329)

diff --git a/packages/flutter_tools/lib/src/build_info.dart b/packages/flutter_tools/lib/src/build_info.dart
index a95da5b..d0ad3d6 100644
--- a/packages/flutter_tools/lib/src/build_info.dart
+++ b/packages/flutter_tools/lib/src/build_info.dart
@@ -382,6 +382,11 @@
   return fs.path.join(getBuildDirectory(), 'ios');
 }
 
+/// Returns the macOS build output directory.
+String getMacOSBuildDirectory() {
+  return fs.path.join(getBuildDirectory(), 'macos');
+}
+
 /// Returns the web build output directory.
 String getWebBuildDirectory() {
   return fs.path.join(getBuildDirectory(), 'web');