ref(node): Add log for running in ESM/CommonJS mode (#12134)

To make debugging etc. easier for us in the future.

Author: mydea

packages/node/src/sdk/init.ts

@@ -173,6 +173,8 @@ function _init(
     client.init();
   }
 
+  logger.log(`Running in ${isCjs() ? 'CommonJS' : 'ESM'} mode.`);
+
   if (options.autoSessionTracking) {
     startSessionTracking();
   }