Refactors armor into dedicated subtypes (#71986)

## About The Pull Request

See title.
## Why It's Good For The Game

Code is cleaner, and more readable/intuitive
Technically closes
https://github.com/tgstation/dev-cycles-initiative/issues/8
## Changelog
🆑
refactor: armor, from the ground up basically
/🆑

Co-authored-by: Mothblocks <35135081+Mothblocks@users.noreply.github.com>

code/game/objects/structures.dm

@@ -10,10 +10,13 @@
 	pass_flags_self = PASSSTRUCTURE
 	blocks_emissive = EMISSIVE_BLOCK_GENERIC
 	var/broken = FALSE
+	armor_type = /datum/armor/obj_structure
+
+/datum/armor/obj_structure
+	fire = 50
+	acid = 50
 
 /obj/structure/Initialize(mapload)
-	if (!armor)
-		armor = list(MELEE = 0, BULLET = 0, LASER = 0, ENERGY = 0, BOMB = 0, BIO = 0, FIRE = 50, ACID = 50)
 	. = ..()
 	if(smoothing_flags & (SMOOTH_CORNERS|SMOOTH_BITMASK))
 		QUEUE_SMOOTH(src)