nitryl and stimulum merge in nitrium (#62061)

This PR is the first of a few were i'll be merging similar working gases into one.
This time is Nitryl and Stimulum. They'll be merged into Nitrium , a brown gas with both features of the two gases
The main scope is to add dept to atmos by removing bloated content and/or repeated content that has never seen the lights of the day (how many times have you seen both gases made and used at the same time?)
The PR so far:
-removed nitryl
-removed stimulum
-merged them into Nitrium (Nitrium is now made with trit, nitrogen and bz from a minimum temperature of 1500 K)
-made Nitrium have both gases features such as fast movements and sleep and stun immunity but increased damage taken
-Nitrium can make crystals that spread the chemicals with a cloud (is still far more efficient to just breathe the gas)

Less rare gases, going towards a better atmos gameplay loop

code/modules/mob/living/carbon/life.dm

@@ -246,10 +246,13 @@
 		else if(bz_partialpressure > 0.01)
 			hallucination += 5
 
-	//NITRYL
-	if(breath_gases[/datum/gas/nitryl])
-		var/nitryl_partialpressure = (breath_gases[/datum/gas/nitryl][MOLES]/breath.total_moles())*breath_pressure
-		adjustFireLoss(nitryl_partialpressure/4)
+	//NITRIUM
+	if(breath_gases[/datum/gas/nitrium])
+		var/nitrium_partialpressure = (breath_gases[/datum/gas/nitrium][MOLES]/breath.total_moles())*breath_pressure
+		if(nitrium_partialpressure > 0.5)
+			adjustFireLoss(nitrium_partialpressure * 0.15)
+		if(nitrium_partialpressure > 5)
+			adjustToxLoss(nitrium_partialpressure * 0.05)
 
 	//FREON
 	if(breath_gases[/datum/gas/freon])