Small ResourceManager refactor, add ResourceSaver<T>.

DaggerFramework/Source/SceneGraph/Entities/Entity.cs

@@ -1,3 +1,4 @@
+using System.Text.Json.Serialization;
 using DaggerFramework.Audio;
 using DaggerFramework.Rendering;
 
@@ -26,4 +27,11 @@ namespace DaggerFramework.SceneGraph
             Layer?.DestroyEntity(Id);
         }
     }
+
+    [JsonSourceGenerationOptions(WriteIndented = true)]
+    [JsonSerializable(typeof(Entity))]
+    internal partial class EntitySourceGenerationContext : JsonSerializerContext
+    {
+
+    }
 }