Clothing fallback (#18258)

* Clothing fallback

Makes clothing have a fallback in the event of a custom species file not having the appropriate icon state.

* some logging

* testing

* swap all unit tests to use icon_exists

* Update poster_tests.dm

* Update clothing_tests.dm

* Update cosmetic_tests.dm

* Update robot_tests.dm

* whoop

* upgrades people, upgrades

* port these

* Update _atom.dm

* adjust all these

* Update clothing.dm

* TRUEFALSE

code/game/objects/items/weapons/storage/wallets.dm

@@ -71,7 +71,7 @@
 	cut_overlays()
 	if(front_id)
 		var/tiny_state = "id-generic"
-		if("id-[front_id.icon_state]" in cached_icon_states(icon))
+		if(icon_exists(icon, "id-[front_id.icon_state]"))
 			tiny_state = "id-"+front_id.icon_state
 		var/image/tiny_image = new/image(icon, icon_state = tiny_state)
 		tiny_image.appearance_flags = RESET_COLOR