[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/atoms_movable.dm

@@ -25,7 +25,10 @@
 	var/inertia_moving = 0
 	var/inertia_next_move = 0
 	var/inertia_move_delay = 5
-	var/pass_flags = 0
+	/// Things we can pass through while moving. If any of this matches the thing we're trying to pass's [pass_flags_self], then we can pass through.
+	var/pass_flags = NONE
+	/// If false makes CanPass call CanPassThrough on this type instead of using default behaviour
+	var/generic_canpass = TRUE
 	var/moving_diagonally = 0 //0: not doing a diagonal move. 1 and 2: doing the first/second step of the diagonal move
 	var/atom/movable/moving_from_pull		//attempt to resume grab after moving instead of before.
 	var/list/acted_explosions	//for explosion dodging
@@ -473,10 +476,15 @@
 /atom/movable/proc/move_crushed(atom/movable/pusher, force = MOVE_FORCE_DEFAULT, direction)
 	return FALSE
 
-/atom/movable/CanPass(atom/movable/mover, turf/target)
+/atom/movable/CanAllowThrough(atom/movable/mover, turf/target)
+	. = ..()
 	if(mover in buckled_mobs)
 		return TRUE
-	return ..()
+
+/// Returns true or false to allow src to move through the blocker, mover has final say
+/atom/movable/proc/CanPassThrough(atom/blocker, turf/target, blocker_opinion)
+	SHOULD_CALL_PARENT(TRUE)
+	return blocker_opinion
 
 /// called when this atom is removed from a storage item, which is passed on as S. The loc variable is already set to the new destination before this is called.
 /atom/movable/proc/on_exit_storage(datum/component/storage/concrete/S) // rename S to master_storage