Fix hanging edges for collapsed nodes after undo/redo

Reduce the amount of `ValidateGraph()` calls when undo/redo'ing to 2 rather than once per node and edge per graph

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Implementation/SerializableGraph.cs

             return new Dictionary<SerializationHelper.TypeSerializationInfo, SerializationHelper.TypeSerializationInfo>();
         }
 
-        public virtual IEdge Connect(SlotReference fromSlotRef, SlotReference toSlotRef)
+        IEdge ConnectNoValidate(SlotReference fromSlotRef, SlotReference toSlotRef)
         {
             if (fromSlotRef == null || toSlotRef == null)
                 return null;
             AddEdgeToNodeEdges(newEdge);
 
             Debug.Log("Connected edge: " + newEdge);
+            return newEdge;
+        }
+
+        public virtual IEdge Connect(SlotReference fromSlotRef, SlotReference toSlotRef)
+        {
+            var newEdge = ConnectNoValidate(fromSlotRef, toSlotRef);
             ValidateGraph();
             return newEdge;
         }
                         removedNodeEdges.Add(edge);
                 }
                 foreach (var edge in removedNodeEdges)
-                    RemoveEdge(edge);
+                    RemoveEdgeNoValidate(edge);
             }
 
             // Remove all nodes and re-add them.
                 foreach (var node in m_Nodes.Values)
                     removedNodeGuids.Add(node.guid);
                 foreach (var nodeGuid in removedNodeGuids)
-                    RemoveNode(m_Nodes[nodeGuid]);
+                    RemoveNodeNoValidate(m_Nodes[nodeGuid]);
+
+            ValidateGraph();
-                    AddNode(node);
+                    AddNodeNoValidate(node);
             }
 
             // Add edges from other graph which don't exist in this one.
-                    Connect(edge.outputSlot, edge.inputSlot);
+                    ConnectNoValidate(edge.outputSlot, edge.inputSlot);
+
+            ValidateGraph();
         }
 
         public void OnEnable()

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/Views/GraphEditorView.cs

                     edgeView.input.Connect(edgeView);
                     m_GraphView.AddElement(edgeView);
                     sourceNodeView.RefreshAnchors();
+                    targetNodeView.RefreshAnchors();
                 }
             }
 
                     edgeView.input = targetAnchor;
                     edgeView.input.Connect(edgeView);
                     m_GraphView.AddElement(edgeView);
+                    sourceNodeView.RefreshAnchors();
+                    targetNodeView.RefreshAnchors();
                 }
             }
         }