Add make ghost role verb (#3204)

Content.Server/GameObjects/Components/Observer/GhostRoles/GhostTakeoverAvailableComponent.cs

@@ -0,0 +1,37 @@
+using System;
+using Content.Server.GameObjects.Components.Mobs;
+using Content.Server.GameObjects.EntitySystems;
+using Content.Server.Players;
+using Robust.Server.Player;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.GameObjects.Components.Observer.GhostRoles
+{
+    /// <summary>
+    ///     Allows a ghost to take over the Owner entity.
+    /// </summary>
+    [RegisterComponent, ComponentReference(typeof(GhostRoleComponent))]
+    public class GhostTakeoverAvailableComponent : GhostRoleComponent
+    {
+        public override string Name => "GhostTakeoverAvailable";
+
+        public override bool Take(IPlayerSession session)
+        {
+            if (Taken)
+                return false;
+
+            Taken = true;
+
+            var mind = Owner.EnsureComponent<MindComponent>();
+
+            if(mind.HasMind)
+                throw new Exception("MindComponent already has a mind!");
+
+            session.ContentData().Mind.TransferTo(Owner);
+
+            EntitySystem.Get<GhostRoleSystem>().UnregisterGhostRole(this);
+
+            return true;
+        }
+    }
+}