Adds a component for ghosting on move. (#3090)

* Adds a component for ghosting on move.
Adds a dummy input mover for IRelayMoveInput to work.

* Add IGhostOnMove

* Fix tests.

Content.Server/GameObjects/Components/Observer/GhostOnMoveComponent.cs

@@ -0,0 +1,41 @@
+#nullable enable
+using System;
+using Content.Server.Commands.Observer;
+using Content.Server.GameObjects.Components.Mobs;
+using Content.Server.GameObjects.Components.Movement;
+using Content.Shared.GameObjects.Components.Movement;
+using Robust.Server.Console;
+using Robust.Shared.Console;
+using Robust.Shared.GameObjects;
+using Robust.Shared.IoC;
+using Robust.Shared.Players;
+using Robust.Shared.Serialization;
+
+namespace Content.Server.GameObjects.Components.Observer
+{
+    [RegisterComponent]
+    [ComponentReference(typeof(IGhostOnMove))]
+    public class GhostOnMoveComponent : Component, IRelayMoveInput, IGhostOnMove
+    {
+        public override string Name => "GhostOnMove";
+
+        public bool CanReturn { get; set; }
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            base.ExposeData(serializer);
+
+            serializer.DataField(this, x => x.CanReturn, "canReturn", true);
+        }
+
+        void IRelayMoveInput.MoveInputPressed(ICommonSession session)
+        {
+            // Let's not ghost if our mind is visiting...
+            if (Owner.HasComponent<VisitingMindComponent>()) return;
+            if (!Owner.TryGetComponent(out MindComponent? mind) || !mind.HasMind || mind.Mind!.IsVisitingEntity) return;
+
+            var host = IoCManager.Resolve<IServerConsoleHost>();
+            new Ghost().Execute(new ConsoleShell(host, session), string.Empty, Array.Empty<string>());
+        }
+    }
+}