Add RequiresGrid component (#23394)

* saving working code

* add checks for deletion

Content.Server/RequiresGrid/RequiresGridComponent.cs

@@ -0,0 +1,11 @@
+namespace Content.Server.RequiresGrid;
+
+/// <summary>
+/// Destroys an entity when they no longer are part of a Grid
+/// </summary>
+[RegisterComponent]
+[Access(typeof(RequiresGridSystem))]
+public sealed partial class RequiresGridComponent : Component
+{
+
+}

Content.Server/RequiresGrid/RequiresGridSystem.cs

@@ -0,0 +1,29 @@
+using Content.Server.Destructible;
+
+namespace Content.Server.RequiresGrid;
+
+public sealed class RequiresGridSystem : EntitySystem
+{
+    [Dependency] private readonly DestructibleSystem _destructible = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<RequiresGridComponent, EntParentChangedMessage>(OnEntParentChanged);
+    }
+
+    private void OnEntParentChanged(EntityUid owner, RequiresGridComponent component, EntParentChangedMessage args)
+    {
+        if (args.OldParent == null)
+            return;
+
+        if (args.Transform.GridUid != null)
+            return;
+
+        if (TerminatingOrDeleted(owner))
+            return;
+
+        _destructible.DestroyEntity(owner);
+    }
+}