refactor: rename action button appearance related variables and procs to be clearer (#25658)

* refactor: make action appearance creation more straightforward

* some adjustments

* fix: adjust action icons to refactor

code/modules/surgery/organs/augments_internal.dm

@@ -377,8 +377,8 @@
 /datum/action/item_action/organ_action/toggle/sensory_enhancer
 	name = "Activate Qani-Laaca System"
 	desc = "Activates your Qani-Laaca computer and grants you its powers. LMB: Short, safer activation. ALT/MIDDLE: Longer, more powerful, more dangerous activation."
-	button_icon = 'icons/obj/surgery.dmi'
-	button_icon_state = "sandy"
+	button_overlay_icon = 'icons/obj/surgery.dmi'
+	button_overlay_icon_state = "sandy"
 	check_flags = AB_CHECK_CONSCIOUS
 	/// Keeps track of how much mephedrone we inject into people on activation
 	var/injection_amount = 10

code/modules/surgery/organs/subtypes/skrell_organs.dm

@@ -17,11 +17,11 @@
 
 /datum/action/item_action/organ_action/toggle/headpocket
 	use_itemicon = FALSE
-	button_icon_state = "skrell_headpocket_in"
+	button_overlay_icon_state = "skrell_headpocket_in"
 
 /obj/item/organ/internal/headpocket/proc/update_button_state()
 	for(var/datum/action/item_action/T in actions)
-		T.button_icon_state = "skrell_headpocket[held_item ? "_out" : "_in"]"
+		T.button_overlay_icon_state = "skrell_headpocket[held_item ? "_out" : "_in"]"
 		T.UpdateButtons()
 
 /obj/item/organ/internal/headpocket/Destroy()