Add 'Scan DNA' function to medical scanner (#1783)

* Add art assets for cloning

* Added a 'Scan DNA' button to the medical scanner

* Made the UI update unconditional for the medical scanner until checks for power changes are in place

* Update Medical scanner to reflect powered status and fix #1774

* added a 'scan dna' button the the medical scanner that will add the contained bodies Uid to a list in CloningSystem, fixed an issue with the menu not populating if the scanner starts in an unpowered state

* Add disabling logic to 'Scan DNA' button on medical scanner

* Removed un-used libraries

* changed scan dna button to Scan and Save DNA

Content.Server/GameObjects/EntitySystems/CloningSystem.cs

@@ -0,0 +1,24 @@
+using System.Collections.Generic;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+
+namespace Content.Server.GameObjects.EntitySystems
+{
+    internal sealed class CloningSystem : EntitySystem
+    {
+        public static List<EntityUid> scannedUids = new List<EntityUid>();
+
+        public static void AddToScannedUids(EntityUid uid)
+        {
+            if (!scannedUids.Contains(uid))
+            {
+                scannedUids.Add(uid);
+            }
+        }
+
+        public static bool HasUid(EntityUid uid)
+        {
+            return scannedUids.Contains(uid);
+        }
+    }
+}