Gravity Generators cannot be unanchored while active (#41256)

* Add unanchor attempt check

* Combine shared component and server component

- Combines SharedGravityGeneratorComponent and GravityGeneratorComponent
- AutoNetworked the GravityActiveBool

* Remove SharedGravityGeneratorComponent

* Update to SharedGravityGeneratorComponent

* Fix to be a complete sentence

* Dirty GravityActive whenever changed

* Rename component and remove view variables

* Update referenced component name

* Move unanchor attempt to shared system

* Add client system

* Revert popup to PopupEntity

* Fix popup to be PopupClient

* Set access restriction on GravityActive

Content.Shared/Gravity/SharedGravityGeneratorSystem.cs

@@ -0,0 +1,29 @@
+using Content.Shared.Popups;
+using Content.Shared.Construction.Components;
+
+namespace Content.Shared.Gravity;
+
+public abstract class SharedGravityGeneratorSystem : EntitySystem
+{
+    [Dependency] private readonly SharedPopupSystem _popupSystem = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<GravityGeneratorComponent, UnanchorAttemptEvent>(OnUnanchorAttempt);
+    }
+
+    /// <summary>
+    /// Prevent unanchoring when gravity is active
+    /// </summary>
+    private void OnUnanchorAttempt(Entity<GravityGeneratorComponent> ent, ref UnanchorAttemptEvent args)
+    {
+        if (!ent.Comp.GravityActive)
+            return;
+
+        _popupSystem.PopupClient(Loc.GetString("gravity-generator-unanchoring-failed"), ent.Owner, args.User, PopupType.Medium);
+
+        args.Cancel();
+    }
+}