Various fire bugfixes (#22431)

Fixes https://github.com/Aurorastation/Aurora.3/issues/22384.
Fixes https://github.com/Aurorastation/Aurora.3/issues/22389.
changes:
  - bugfix: "Fixes turf fires not spreading."
  - bugfix: "Fixes atmos fires not consistently igniting."
  - bugfix: "Fixes dead mobs burning forever."
  - bugfix: "Fixes fire_act() runtimes for multiple objects."

code/modules/mob/living/living_defense.dm

@@ -442,14 +442,19 @@
 		fire_stacks = min(0, ++fire_stacks) //If we've doused ourselves in water to avoid fire, dry off slowly
 
 	if(!on_fire)
-		return 1
+		return TRUE
+
+	// If we're dead, slowly put out the fire.
+	if(((stat & DEAD) || (status_flags & FAKEDEATH)) && fire_stacks > 0 )
+		fire_stacks--
+
 	else if(fire_stacks <= 0)
 		ExtinguishMobCompletely() //Fire's been put out.
-		return 1
+		return TRUE
 
 	if(environment.gas[GAS_OXYGEN] < 1)
 		ExtinguishMobCompletely() //If there's no oxygen in the tile we're on, put out the fire
-		return 1
+		return TRUE
 
 	var/turf/location = get_turf(src)
 	location.hotspot_expose(fire_burn_temperature(environment), 50, 1)