test: convert test to ESM

Replace CommonJS require() with ESM imports, add "type": "module"
to test/package.json, remove 'use strict' and jshint directives,
replace __dirname with import.meta.dirname.

Made-with: Cursor

test/package.json

@@ -14,5 +14,6 @@
     "mocha": "^11.7.4",
     "selenium-webdriver": "^4.36.0",
     "superagent": "^10.2.3"
-  }
+  },
+  "type": "module"
 }