Add Composer Stager to Core vendor hardening config

AFAICT we won't need this anymore after 📌 Add symlink support to Composer Stager 2.0, require that version, and simplify UX & tests accordingly Fixed is done?

… and otherwise this would need to be core-mvp because Automatic Updates would be unable to work? 😅

#5 why won't it work? Do those directories contain symlinks?

I was wrong — I misinterpreted the issue summary as implying that Composer Stager itself contains symlinks … and since it complains about symlinks in the codebase… that'd have been an interesting catch-22 🤣

All clear now! 👍

IMHO this should be done as part of 📌 Finalize \Drupal\automatic_updates\Development\Converter script to update core MR Fixed .