[HERCULES] Extended item_check to also add unique_ids to any non-stackable items that lack it
- This is useful in case an old server that didn't have the unique_id feature enabled is updated to the latest version.
- It'll only have effect if item_check is enabled in the configuration files.
https://github.com/HerculesWS/Hercules/commit/49d60479ac8a7ad2a9e51a9c2afd699f3fac8069