fix: Adds generic entity persistence support and BOBEntry as entities (#1527)

### Summary
Adds a generic entity persistence. This can be used to create new entity types that have a `Serial`.

Here is an example:

```cs
public class BOBEntries : GenericEntitySerialization<IBOBEntry>
{
    public static void Configure()
    {
        Configure("BOBEntries");
    }
}
```

The annotation tells the system what folder to serialize the entries to. The class/interface (`IBOBEntry`) is the root type that implements `ISerializable`.

Projects/Server/Items/Item.cs

@@ -760,9 +760,6 @@ public class Item : IHued, IComparable<Item>, ISpawnable, IObjectPropertyListEnt
     [CommandProperty(AccessLevel.GameMaster, readOnly: true)]
     public DateTime Created { get; set; } = Core.Now;
 
-    [CommandProperty(AccessLevel.GameMaster)]
-    DateTime ISerializable.LastSerialized { get; set; } = Core.Now;
-
     long ISerializable.SavePosition { get; set; } = -1;
 
     BufferWriter ISerializable.SaveBuffer { get; set; }