Initial 1.20.5 support

[tal5]

Won't go into detail about everything, but overall:

• NMS changes to Enchantments, items, packets, and a few other stuff - fixed whatever's reasonably small and added a TODO for any large rewrite changes
• Some API changes actually, again fixed small ones and added TODO for large ones; will need to decide what to do compatibility wise as this could break some scripts.
• Added a few other TODOs as I was going over things for general changes we can/should make for 1.20.5 (imo, ofc).
• ItemHelper#clearDenizenRecipes had some NMS breakages, so removed it in favor of Bukkit#recipeIterator which exists on all supported versions - it does looks like it might have some issues on Spigot that Paper fixed? but imo as long as it doesn't completely blow up or anything & is a lot nicer than NMS we can keep it this way, lmk if you want to make 100% sure Spigot compact is kept and go back to NMS though.
• Updated SpecialSource on the 1.20 module for Java 21 support.

[tal5]

Updated Paper to 1.20.5 & accounted for new Spigot changes

[tal5]

Bumped to 1.20.6