[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/controllers/subsystem/throwing.dm

@@ -200,6 +200,6 @@ SUBSYSTEM_DEF(throwing)
 		var/atom/movable/AM = thing
 		if (AM == thrownthing || (AM == thrower && !ismob(thrownthing)))
 			continue
-		if (AM.density && !(AM.pass_flags & LETPASSTHROW) && !(AM.flags_1 & ON_BORDER_1))
+		if (AM.density && !(AM.pass_flags_self & LETPASSTHROW) && !(AM.flags_1 & ON_BORDER_1))
 			finalize(hit=TRUE, target=AM)
 			return TRUE