Pathfinder rework (#11452)

Content.Shared/NPC/PathPoly.cs

@@ -0,0 +1,32 @@
+using Robust.Shared.Map;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.NPC;
+
+/*
+ * I bikeshedded a lot on how to do this and I'm still not entirely happy.
+ * The main thing is you need a weak ref to the poly because it may be invalidated due to graph updates.
+ * I had a struct version but you still need to store the neighbors somewhere, maybe on the chunk itself?
+ * Future dev work required.
+ */
+
+/// <summary>
+/// A path poly to be used for networked debug purposes.
+/// </summary>
+[Serializable, NetSerializable]
+public sealed class DebugPathPoly
+{
+    public EntityUid GraphUid;
+    public Vector2i ChunkOrigin;
+    public byte TileIndex;
+
+    public Box2 Box;
+    public PathfindingData Data;
+    public List<EntityCoordinates> Neighbors = default!;
+}
+
+[Serializable, NetSerializable]
+public sealed class DebugPathPolyNeighbor
+{
+    public EntityCoordinates Coordinates;
+}