Fix a bunch of compiler warnings (#10518)

Content.Client/Light/LanternVisualizer.cs

@@ -30,6 +30,7 @@ namespace Content.Client.Light
             }
         };
 
+        [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
         public override void OnChangeData(AppearanceComponent component)
         {
             base.OnChangeData(component);

Content.Client/Light/Visualizers/EmergencyLightVisualizer.cs

@@ -9,6 +9,7 @@ namespace Content.Client.Light.Visualizers
     [DataDefinition]
     public sealed class EmergencyLightVisualizer : AppearanceVisualizer
     {
+        [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
         public override void OnChangeData(AppearanceComponent component)
         {
             base.OnChangeData(component);

Content.Client/Light/Visualizers/ExpendableLightVisualizer.cs

@@ -12,6 +12,7 @@ namespace Content.Client.Light.Visualizers
     [UsedImplicitly]
     public sealed class ExpendableLightVisualizer : AppearanceVisualizer
     {
+        [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
         public override void OnChangeData(AppearanceComponent component)
         {
             base.OnChangeData(component);

Content.Client/Light/Visualizers/FlashLightVisualizer.cs

@@ -57,6 +57,7 @@ namespace Content.Client.Light.Visualizers
         private Action<string>? _radiatingCallback;
         private Action<string>? _blinkingCallback;
 
+        [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
         public override void OnChangeData(AppearanceComponent component)
         {
             base.OnChangeData(component);

Content.Client/Light/Visualizers/LightBulbVisualizer.cs

@@ -10,6 +10,7 @@ namespace Content.Client.Light.Visualizers
     [UsedImplicitly]
     public sealed class LightBulbVisualizer : AppearanceVisualizer
     {
+        [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
         public override void OnChangeData(AppearanceComponent component)
         {
             base.OnChangeData(component);

Content.Client/Light/Visualizers/PoweredLightVisualizer.cs

@@ -19,6 +19,7 @@ namespace Content.Client.Light.Visualizers
 
         private Action<string>? _blinkingCallback;
 
+        [Obsolete("Subscribe to AppearanceChangeEvent instead.")]
         public override void OnChangeData(AppearanceComponent component)
         {
             base.OnChangeData(component);