fix process.env replacements in webpack producing invalid syntax

Author: JReinhold

code/builders/builder-webpack5/src/preview/iframe-webpack.config.ts

@@ -194,7 +194,7 @@ export default async (
         },
       }),
       new DefinePlugin({
-        'process.env': JSON.stringify(envs),
+        'process.env': `(${JSON.stringify(envs)})`,
         ...stringifyProcessEnvs(envs),
         NODE_ENV: JSON.stringify(
           features?.developmentModeForBuild && isProd ? 'development' : process.env.NODE_ENV