Implements usage of the REVERSE_DIR macro throughout the code. (#77122)

## About The Pull Request
Replaces a ton of `turn(dir, 180)` calls with the aforementioned macro.

## Why It's Good For The Game
Afaik, `REVERSE_DIR` was coded to be faster than the classic `turn(dir,
180)` call, being a simple set of binary operations. To sum it up, micro
optimization.

## Changelog

N/A

code/modules/admin/fun_balloon.dm

@@ -142,7 +142,7 @@
 	for (var/S in SSshuttle.stationary_docking_ports)
 		var/obj/docking_port/stationary/SM = S
 		if (SM.shuttle_id == "emergency_home")
-			var/new_dir = turn(SM.dir, 180)
+			var/new_dir = REVERSE_DIR(SM.dir)
 			SM.forceMove(get_ranged_target_turf(SM, new_dir, crash_strength))
 			break
 

code/modules/admin/verbs/mapping.dm

@@ -126,7 +126,7 @@ GLOBAL_LIST_EMPTY(dirty_vars)
 			if(!(locate(/obj/structure/grille) in T))
 				var/window_check = 0
 				for(var/obj/structure/window/W in T)
-					if (W.dir == turn(C1.dir,180) || (W.dir in list(NORTHEAST,SOUTHEAST,NORTHWEST,SOUTHWEST)) )
+					if (W.dir == REVERSE_DIR(C1.dir) || (W.dir in list(NORTHEAST,SOUTHEAST,NORTHWEST,SOUTHWEST)) )
 						window_check = 1
 						break
 				if(!window_check)