fix: fix codegen script failing due to missing platforms

there is a regression in the codegen script that assumes `platforms` field to be present.
so we add empty objects to avoid the crash during code generation.

packages/create-react-native-library/templates/native-common-example/example/react-native.config.js

@@ -25,6 +25,12 @@ module.exports = {
   dependencies: {
     [pkg.name]: {
       root: path.join(__dirname, '..'),
+      platforms: {
+        // Codegen script incorrectly fails without this
+        // So we explicitly specify the platforms with empty object
+        ios: {},
+        android: {},
+      },
     },
   },
 };