Implement machine linking (#1784)

* Implement machine linking

* Cleanup and rename Signals

* Implement signal button

* Add machine linking signal mapping

* Fix signallink command help

* Add localization to signal linking and allow infinite range

* Add feedback for when a transmitter is not connected to any receivers

Refactor PopupMessage to use the entity extension
Refactor dependencies to not have to disable warnings

Content.Server/GameObjects/Components/MachineLinking/ISignalReceiver.cs

@@ -0,0 +1,14 @@
+namespace Content.Server.GameObjects.Components.MachineLinking
+{
+    public interface ISignalReceiver
+    {
+        void TriggerSignal(SignalState state);
+    }
+
+    public enum SignalState
+    {
+        On,
+        Off,
+        Toggle
+    }
+}