Remove Uncross() and CheckExit(), add connect_loc element to cover the cases we used it for (#58188)

* Remove Uncross(), add create_loc element

* Update on ChangeTurf

* Explicit return

* Hold onto elements and remove TEST_FOCUS

* Remove UNIT_TESTS compile flag

* Follow my own advice.

* Comment about Uncross + CRASH

* Remove /atom/Exit ..()

* Apply suggestions from code review

Co-authored-by: Emmett Gaines <ninjanomnom@gmail.com>

* Use keyed locs

* Re-add Bump()

* Superfluous check

* Correct change turf signal, remove old continue check

* Fix compile failure

* Fix tests

* Don't create element for fulltile windows

* Correctly unregister old location

Co-authored-by: Emmett Gaines <ninjanomnom@gmail.com>

code/game/objects/structures/window.dm

@@ -68,6 +68,13 @@
 	flags_1 |= ALLOW_DARK_PAINTS_1
 	RegisterSignal(src, COMSIG_OBJ_PAINTED, .proc/on_painted)
 
+	var/static/list/loc_connections = list(
+		COMSIG_ATOM_EXIT = .proc/on_exit,
+	)
+
+	if (flags_1 & ON_BORDER_1)
+		AddElement(/datum/element/connect_loc, loc_connections)
+
 /obj/structure/window/ComponentInitialize()
 	. = ..()
 	AddComponent(/datum/component/simple_rotation,ROTATION_ALTCLICK | ROTATION_CLOCKWISE | ROTATION_COUNTERCLOCKWISE | ROTATION_VERBS ,null,CALLBACK(src, .proc/can_be_rotated),CALLBACK(src,.proc/after_rotation))
@@ -117,13 +124,18 @@
 
 	return TRUE
 
-/obj/structure/window/CheckExit(atom/movable/O, turf/target)
-	if(istype(O) && (O.pass_flags & pass_flags_self))
-		return TRUE
-	if(!fulltile && get_dir(O.loc, target) == dir)
-		return !density
-	return TRUE
+/obj/structure/window/proc/on_exit(datum/source, atom/movable/leaving, atom/new_location)
+	SIGNAL_HANDLER
 
+	if (istype(leaving) && (leaving.pass_flags & pass_flags_self))
+		return
+
+	if (fulltile)
+		return
+
+	if(get_dir(leaving.loc, new_location) == dir && density)
+		leaving.Bump(src)
+		return COMPONENT_ATOM_BLOCK_EXIT
 
 /obj/structure/window/attack_tk(mob/user)
 	user.changeNext_move(CLICK_CD_MELEE)