Refactored fire_act (#19158)

Refactored fire_act() to be in line with TG version, removed useless
parameter, added signal, made non sleepable and forced to call parent.
Added atom_act.dm file for the various *_act procs.

code/modules/overmap/exoplanets/decor/flora/potted_big.dm

@@ -24,7 +24,7 @@
 	death()
 	return ..()
 
-/obj/structure/flora/pottedplant/fire_act()
+/obj/structure/flora/pottedplant/fire_act(exposed_temperature, exposed_volume)
 	death()
 	return ..()
 

code/modules/overmap/exoplanets/decor/flora/potted_small.dm

@@ -19,7 +19,7 @@
 	death()
 	return ..()
 
-/obj/item/flora/pottedplant_small/fire_act()
+/obj/item/flora/pottedplant_small/fire_act(exposed_temperature, exposed_volume)
 	death()
 	return ..()
 

code/modules/overmap/exoplanets/decor/turfs/snow.dm

@@ -20,7 +20,8 @@
 	SSicon_smooth.add_to_queue_neighbors(src)
 	SSicon_smooth.add_to_queue(src)
 
-/turf/simulated/floor/exoplanet/snow/fire_act(datum/gas_mixture/air, exposed_temperature, exposed_volume)
+/turf/simulated/floor/exoplanet/snow/fire_act(exposed_temperature, exposed_volume)
+	. = ..()
 	melt()
 
 /turf/simulated/floor/exoplanet/snow/melt()

code/modules/overmap/ship_weaponry/_ship_ammunition.dm

@@ -105,7 +105,9 @@
 	if(ammunition_flags & SHIP_AMMO_FLAG_INFLAMMABLE)
 		cookoff(TRUE)
 
-/obj/item/ship_ammunition/fire_act(datum/gas_mixture/air, exposed_temperature, exposed_volume)
+/obj/item/ship_ammunition/fire_act(exposed_temperature, exposed_volume)
+	. = ..()
+
 	if(ammunition_flags & SHIP_AMMO_FLAG_INFLAMMABLE)
 		if(exposed_temperature >= T0C+200)
 			cookoff(TRUE)

code/modules/overmap/ship_weaponry/weaponry/longbow_ammo.dm

@@ -155,7 +155,9 @@
 /obj/item/warhead/longbow/ex_act(severity)
 	cookoff(TRUE)
 
-/obj/item/warhead/longbow/fire_act(datum/gas_mixture/air, exposed_temperature, exposed_volume)
+/obj/item/warhead/longbow/fire_act(exposed_temperature, exposed_volume)
+	. = ..()
+
 	if(exposed_temperature >= T0C+200)
 		cookoff(TRUE)