Minor enchantment cache refactor (#82371)

* Remove 0.H legacy enchant_vals, only serialise values and skills if modified

* Redo the enchant_vals and skills, also deal with melee_damage_bonus, encumbrance_modifier, incoming_damage_mod and incoming_damage_mod_post_absorbed

* Reredo it the first way and template it for everything but enchant_mods which needs slightly awkward handling

* IWYU

* Appease our clang overlords

Author: Procyonae