Shadekin and Xenochimera variable refactor (#17651)

* gets rid of xenochimera brain var

* whoops

* shadekin too

ye https://i.imgur.com/lNI2AiG.png

* organize

* simplekin too

* yuh

* Refactors xenochimera

progress:
https://i.imgur.com/ssQbRKS.png
https://i.imgur.com/ySBxm0M.png
https://i.imgur.com/3FWPVuP.png

* Update xenochimera.dm

* Update examine_vr.dm

* Update xenochimera.dm

* Update xenochimera.dm

code/modules/organs/internal/brain.dm

@@ -19,7 +19,6 @@ GLOBAL_LIST_BOILERPLATE(all_brain_organs, /obj/item/organ/internal/brain)
 	var/mob/living/carbon/brain/brainmob = null
 	var/can_assist = TRUE
 	var/defib_timer = -1
-	var/laststress = 0
 
 /obj/item/organ/internal/brain/process()
 	..()

code/modules/organs/subtypes/shadekin.dm

@@ -1,6 +1,2 @@
 /obj/item/organ/internal/brain/shadekin
 	can_assist = FALSE
-
-	var/dark_energy = 100
-	var/max_dark_energy = 100
-	var/dark_energy_infinite = FALSE