[DNM][DNM][WIP] Projectile backend code port and update

Ports#54924,  #65061, #59804 from /tg.
adds auxiliary code from /tg to make code work.

code/game/machinery/deployable.dm

@@ -37,22 +37,19 @@
 	else
 		return ..()
 
-/obj/structure/barricade/CanPass(atom/movable/mover, turf/target)//So bullets will fly over and stuff.
+/obj/structure/barricade/CanAllowThrough(atom/movable/mover, turf/target)//So bullets will fly over and stuff.
+	. = ..()
 	if(locate(/obj/structure/barricade) in get_turf(mover))
-		return 1
+		return TRUE
 	else if(istype(mover, /obj/item/projectile))
 		if(!anchored)
-			return 1
+			return TRUE
 		var/obj/item/projectile/proj = mover
 		if(proj.firer && Adjacent(proj.firer))
-			return 1
+			return TRUE
 		if(prob(proj_pass_rate))
-			return 1
-		return 0
-	else
-		return !density
-
-
+			return TRUE
+		return FALSE
 
 /////BARRICADE TYPES///////
 
@@ -79,7 +76,6 @@
 		return
 	return ..()
 
-
 /obj/structure/barricade/wooden/crude
 	name = "crude plank barricade"
 	desc = "This space is blocked off by a crude assortment of planks."
@@ -96,7 +92,6 @@
 /obj/structure/barricade/wooden/make_debris()
 	new /obj/item/stack/sheet/mineral/wood(get_turf(src), drop_amount)
 
-
 /obj/structure/barricade/sandbags
 	name = "sandbags"
 	desc = "Bags of sand. Self explanatory."
@@ -104,13 +99,12 @@
 	icon_state = "sandbags"
 	max_integrity = 280
 	proj_pass_rate = 20
-	pass_flags = LETPASSTHROW
+	pass_flags_self = LETPASSTHROW
 	bar_material = SAND
 	climbable = TRUE
 	smooth = SMOOTH_TRUE
 	canSmoothWith = list(/obj/structure/barricade/sandbags, /turf/closed/wall, /turf/closed/wall/r_wall, /obj/structure/falsewall, /obj/structure/falsewall/reinforced, /turf/closed/wall/rust, /turf/closed/wall/r_wall/rust, /obj/structure/barricade/security)
 
-
 /obj/structure/barricade/security
 	name = "security barrier"
 	desc = "A deployable barrier. Provides good cover in fire fights."
@@ -125,7 +119,6 @@
 	var/deploy_time = 40
 	var/deploy_message = TRUE
 
-
 /obj/structure/barricade/security/Initialize()
 	. = ..()
 	addtimer(CALLBACK(src, .proc/deploy), deploy_time)
@@ -137,7 +130,6 @@
 	if(deploy_message)
 		visible_message("<span class='warning'>[src] deploys!</span>")
 
-
 /obj/item/grenade/barrier
 	name = "barrier grenade"
 	desc = "Instant cover."
@@ -194,7 +186,6 @@
 /obj/item/grenade/barrier/ui_action_click(mob/user)
 	toggle_mode(user)
 
-
 #undef SINGLE
 #undef VERTICAL
 #undef HORIZONTAL