Mob AI Tweaks

-Added wither_boss_drops_netherite config, which allows the wither to drop netherite scrap on death. True by default.

-Added whitelists/seats_hostiles_can_escape, accepts list of entity IDs of vehicles or block IDs of chairs a hostile mob can escape from if they ever get stuck in them.

-Added escapable_seats datapack tag that does the above but only takes entities and not blocks. Contains only #c:boats by default.

-Fixed Wither Skeletons and Zombified Piglins not having the ability to spawn with enchanted bows/crossbows since they can both spawn with enchanted swords. (Dev Note: Not sure why, but despite these two mobs being specifically coded to never spawn with their weapons enchanted in vanilla, they still do???)