[lls] Annotate npcUtil global, correct issues identified

[claywar]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

• Adds Lua Language Server annotations to npcUtil functions and corrects issues identified from them
• Adds additional item enum entries

Steps to test these changes

CI should pass, quests should function normally along with no other impact to gameplay