Firealarms now have a separate icon when alarming (#18988)

* Updates icons and code

* Adds suggested dmdoc comment.

* Heathen Mobile Webedit for Suggestions

* Suggestions, again.

I'm not going to change this again, unless a maint tells me to.

Co-authored-by: Charlie <69320440+hal9000PR@users.noreply.github.com>

Co-authored-by: Charlie <69320440+hal9000PR@users.noreply.github.com>

code/game/machinery/firealarm.dm

@@ -11,6 +11,7 @@ FIRE ALARM
 	desc = "<i>\"Pull this in case of emergency\"</i>. Thus, keep pulling it forever."
 	icon = 'icons/obj/monitors.dmi'
 	icon_state = "firealarm_on"
+	/// Whether or not the fire alarm will sound the alarm if its temperature rises above 200C
 	var/detecting = TRUE
 	var/working = TRUE
 	var/time = 10.0
@@ -50,10 +51,18 @@ FIRE ALARM
 		return
 	if(stat & BROKEN)
 		icon_state = "firealarm_broken"
-	else if(stat & NOPOWER)
+		return
+	if(stat & NOPOWER)
 		icon_state = "firealarm_off"
-	else if(!detecting)
+		return
+	
+	var/area/area = get_area(src)
+	if(area.fire)
+		icon_state = "firealarm_alarming"
+		return
+	if(!detecting)
 		icon_state = "firealarm_detect"
+		return
 	else
 		icon_state = "firealarm_on"