Drag changes (#2487)

* Drag changes

* Higlights only show near cursor
* Don't highlight un-droppable entities
* Fixes invalid highlights issue

* Also the scanner

* 2 months fix

* Address reviews

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Server/GameObjects/EntitySystems/AI/Pathfinding/PathfindingSystem.cs

@@ -306,7 +306,8 @@ namespace Content.Server.GameObjects.EntitySystems.AI.Pathfinding
             // If we've moved to space or the likes then remove us.
             if (moveEvent.Sender.Deleted ||
                 !moveEvent.Sender.TryGetComponent(out IPhysicsComponent physics) ||
-                !PathfindingNode.IsRelevant(moveEvent.Sender, physics))
+                !PathfindingNode.IsRelevant(moveEvent.Sender, physics) ||
+                moveEvent.NewPosition.GetGridId(EntityManager) == GridId.Invalid)
             {
                 HandleEntityRemove(moveEvent.Sender);
                 return;

Content.Server/GameObjects/EntitySystems/Click/InteractionSystem.cs

@@ -71,6 +71,7 @@ namespace Content.Server.GameObjects.EntitySystems.Click
             var interactionArgs = new DragDropEventArgs(performer, msg.DropLocation, dropped, target);
 
             // must be in range of both the target and the object they are drag / dropping
+            // Client also does this check but ya know we gotta validate it.
             if (!interactionArgs.InRangeUnobstructed(ignoreInsideBlocker: true, popup: true)) return;
 
             // trigger dragdrops on the dropped entity