src: use unique_ptr for CachedData in ContextifyScript::New

This closes a memory leak.

PR-URL: https://github.com/nodejs/node/pull/33113


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>