Resolves ThrusterVisualizer is Obsolete (#13904)

Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Client/Shuttles/ThrusterSystem.cs

@@ -0,0 +1,51 @@
+using Content.Shared.Shuttles.Components;
+using Robust.Client.GameObjects;
+
+namespace Content.Client.Shuttles;
+
+/// <summary>
+/// Handles making a thruster visibly turn on/emit an exhaust plume according to its state. 
+/// </summary>
+public sealed class ThrusterSystem : VisualizerSystem<ThrusterComponent>
+{
+    /// <summary>
+    /// Updates whether or not the thruster is visibly active/thrusting.
+    /// </summary>
+    protected override void OnAppearanceChange(EntityUid uid, ThrusterComponent comp, ref AppearanceChangeEvent args)
+    {
+        if (args.Sprite == null
+        || !AppearanceSystem.TryGetData<bool>(uid, ThrusterVisualState.State, out var state, args.Component))
+            return;
+
+        args.Sprite.LayerSetVisible(ThrusterVisualLayers.ThrustOn, state);
+        SetThrusting(
+            uid,
+            state && AppearanceSystem.TryGetData<bool>(uid, ThrusterVisualState.Thrusting, out var thrusting, args.Component) && thrusting,
+            args.Sprite
+        );
+    }
+
+    /// <summary>
+    /// Sets whether or not the exhaust plume of the thruster is visible or not.
+    /// </summary>
+    private static void SetThrusting(EntityUid _, bool value, SpriteComponent sprite)
+    {
+        if (sprite.LayerMapTryGet(ThrusterVisualLayers.Thrusting, out var thrustingLayer))
+        {
+            sprite.LayerSetVisible(thrustingLayer, value);
+        }
+
+        if (sprite.LayerMapTryGet(ThrusterVisualLayers.ThrustingUnshaded, out var unshadedLayer))
+        {
+            sprite.LayerSetVisible(unshadedLayer, value);
+        }
+    }
+}
+
+public enum ThrusterVisualLayers : byte
+{
+    Base,
+    ThrustOn,
+    Thrusting,
+    ThrustingUnshaded,
+}