Fix a bunch of compiler warnings (#10518)

Content.Client/Computer/ComputerVisualizer.cs

@@ -20,6 +20,7 @@ namespace Content.Client.Computer
         private string BodyBrokenState = "broken";
         private string ScreenBroken = "computer_broken";
 
+        [Obsolete("Subscribe to your component being initialised instead.")]
         public override void InitializeEntity(EntityUid entity)
         {
             base.InitializeEntity(entity);
@@ -35,6 +36,7 @@ namespace Content.Client.Computer
             }
         }
 
+        [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
         public override void OnChangeData(AppearanceComponent component)
         {
             base.OnChangeData(component);