ApcNet updating fix (#3078)

* GridPowerComponent

* ApcNet Powered update bugfix

* PowerTest fix

* Add GridPower to Saltern

* test fix

* Update canceling cleanup

* code cleanup

* nullable & code cleanup for test

* undo power test nullable

* Replaces GridPowerSystem with ApcNetSystem

* build fix

* Update Content.Server/GameObjects/EntitySystems/ApcNetSystem.cs

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.Server/GameObjects/Components/NodeContainer/NodeGroups/INodeGroup.cs

@@ -36,6 +36,12 @@ namespace Content.Server.GameObjects.Components.NodeContainer.NodeGroups
         [ViewVariables]
         public int NodeCount => Nodes.Count;
 
+        /// <summary>
+        ///     Debug variable to indicate that this NodeGroup should not be being used by anything.
+        /// </summary>
+        [ViewVariables]
+        public bool Removed { get; private set; } = false;
+
         public static readonly INodeGroup NullGroup = new NullNodeGroup();
 
         protected GridId GridId { get; private set;}
@@ -70,6 +76,7 @@ namespace Content.Server.GameObjects.Components.NodeContainer.NodeGroups
             {
                 node.NodeGroup = newGroup;
             }
+            Removed = true;
         }
 
         /// <summary>
@@ -92,6 +99,7 @@ namespace Content.Server.GameObjects.Components.NodeContainer.NodeGroups
                 }
             }
             AfterRemake(newGroups);
+            Removed = true;
         }
 
         protected virtual void OnAddNode(Node node) { }