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/SignalButtonComponent.cs

@@ -0,0 +1,40 @@
+using Content.Shared.Interfaces;
+using Content.Shared.Interfaces.GameObjects.Components;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Interfaces.GameObjects;
+using Robust.Shared.Localization;
+
+namespace Content.Server.GameObjects.Components.MachineLinking
+{
+    [RegisterComponent]
+    public class SignalButtonComponent : Component, IActivate, IInteractHand
+    {
+        public override string Name => "SignalButton";
+
+        public void Activate(ActivateEventArgs eventArgs)
+        {
+            TransmitSignal(eventArgs.User);
+        }
+
+        public bool InteractHand(InteractHandEventArgs eventArgs)
+        {
+            TransmitSignal(eventArgs.User);
+            return true;
+        }
+
+        private void TransmitSignal(IEntity user)
+        {
+            if (!Owner.TryGetComponent<SignalTransmitterComponent>(out var transmitter))
+            {
+                return;
+            }
+
+            if (transmitter.TransmitSignal(user, SignalState.Toggle))
+            {
+                // Since the button doesn't have an animation, I'm going to use a popup message
+                Owner.PopupMessage(user, Loc.GetString("Click."));
+            }
+        }
+
+    }
+}