Add basic PDA/Syndicate Uplink. (#942)

Co-authored-by: FL-OZ <anotherscuffed@gmail.com>
Co-authored-by: Pieter-Jan Briers <pieterjan.briers+git@gmail.com>

Content.Client/GameObjects/Components/PDA/PDAVisualizer.cs

@@ -0,0 +1,38 @@
+using Content.Shared.GameObjects.Components.PDA;
+using Robust.Client.GameObjects;
+using Robust.Client.Interfaces.GameObjects.Components;
+
+namespace Content.Client.GameObjects.Components.PDA
+{
+    public class PDAVisualizer : AppearanceVisualizer
+    {
+
+        private enum PDAVisualLayers
+        {
+            Base,
+            Unlit
+        }
+
+
+        public override void OnChangeData(AppearanceComponent component)
+        {
+            base.OnChangeData(component);
+            if (component.Owner.Deleted)
+            {
+                return;
+            }
+            var sprite = component.Owner.GetComponent<ISpriteComponent>();
+            sprite.LayerSetVisible(PDAVisualLayers.Unlit, false);
+            if(!component.TryGetData<bool>(PDAVisuals.ScreenLit, out var isScreenLit))
+            {
+                return;
+            }
+            sprite.LayerSetState(PDAVisualLayers.Unlit, "unlit_pda_screen");
+            sprite.LayerSetVisible(PDAVisualLayers.Unlit, isScreenLit);
+
+
+        }
+
+
+    }
+}