🔨 Refactor conquest.lua - Overseer Lookup

[claywar]

• [x] I have paid attention to this example and will edit again if need be to not break the formatting, or I will be ignored
• [x] I have searched existing issues to see if the issue has already been opened, and I have checked the commit log to see if the issue has been resolved since my server was last updated
• [x] I have read and understood the Contributing Guide

Describe the feature

Dynamic lookup requires that the npc or mob name be used as the naming convention in IDs.lua.

Add lookup table to conquest.lua global so that OVERSEER_BASE can be deprecated, and use dynamic lookup on the relevant NPCs.