fix(build): Copy vendor files to lib/

Author: manueliglesias

packages/aws-appsync/package.json

@@ -14,7 +14,7 @@
     "url": "https://github.com/awslabs/aws-mobile-appsync-sdk-js.git"
   },
   "scripts": {
-    "prepare": "tsc"
+    "prepare": "tsc && cp -r src/vendor lib/vendor"
   },
   "dependencies": {
     "@redux-offline/redux-offline": "^2.2.1",