[MIRROR] Fix Xenomorphs not being able to generate plasma for their abilities. (#1752)

* Fix Xenomorphs not being able to generate plasma for their abilities. (#55051)

Fixes #55006

#54632 added some code to handle organ processing, including a big ol' global list which defines the organ processing order.

Downside to this is that it didn't take account of 5 year old Xenomorph code where the organ slots weren't defines. As a result, `/mob/living/carbon/proc/handle_organs()` would never call the `on_life()` for Xeno organs as they weren't in the big ol' global list.

I created defines for Xeno organs, added them to the global list and updated the organs with the new defines. As a result, Xeno plasma vessels now have their `on_life()` proc fired once again and generate plasma.

In local testing I was generating the expected amount of plasma on and off weeds and was able to successfully evolve up to a Queen.

* Fix Xenomorphs not being able to generate plasma for their abilities.

Co-authored-by: Timberpoes <silent_insomnia_pp@hotmail.co.uk>

code/modules/mob/living/carbon/alien/organs.dm

@@ -31,7 +31,7 @@
 	icon_state = "plasma"
 	w_class = WEIGHT_CLASS_NORMAL
 	zone = BODY_ZONE_CHEST
-	slot = "plasmavessel"
+	slot = ORGAN_SLOT_XENO_PLASMAVESSEL
 	alien_powers = list(/obj/effect/proc_holder/alien/plant, /obj/effect/proc_holder/alien/transfer)
 	food_reagents = list(/datum/reagent/consumable/nutriment = 5, /datum/reagent/toxin/plasma = 10)
 
@@ -101,7 +101,7 @@
 	name = "hive node"
 	icon_state = "hivenode"
 	zone = BODY_ZONE_HEAD
-	slot = "hivenode"
+	slot = ORGAN_SLOT_XENO_HIVENODE
 	w_class = WEIGHT_CLASS_TINY
 	///Indicates if the queen died recently, aliens are heavily weakened while this is active.
 	var/recent_queen_death = FALSE
@@ -156,7 +156,7 @@
 	name = "resin spinner"
 	icon_state = "stomach-x"
 	zone = BODY_ZONE_PRECISE_MOUTH
-	slot = "resinspinner"
+	slot = ORGAN_SLOT_XENO_RESINSPINNER
 	alien_powers = list(/obj/effect/proc_holder/alien/resin)
 
 
@@ -164,7 +164,7 @@
 	name = "acid gland"
 	icon_state = "acid"
 	zone = BODY_ZONE_PRECISE_MOUTH
-	slot = "acidgland"
+	slot = ORGAN_SLOT_XENO_ACIDGLAND
 	alien_powers = list(/obj/effect/proc_holder/alien/acid)
 
 
@@ -172,7 +172,7 @@
 	name = "neurotoxin gland"
 	icon_state = "neurotox"
 	zone = BODY_ZONE_PRECISE_MOUTH
-	slot = "neurotoxingland"
+	slot = ORGAN_SLOT_XENO_NEUROTOXINGLAND
 	alien_powers = list(/obj/effect/proc_holder/alien/neurotoxin)
 
 
@@ -180,6 +180,6 @@
 	name = "egg sac"
 	icon_state = "eggsac"
 	zone = BODY_ZONE_PRECISE_GROIN
-	slot = "eggsac"
+	slot = ORGAN_SLOT_XENO_EGGSAC
 	w_class = WEIGHT_CLASS_BULKY
 	alien_powers = list(/obj/effect/proc_holder/alien/lay_egg)