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/UOContent/Accounting/Account.cs

@@ -290,9 +290,6 @@ namespace Server.Accounting
         [CommandProperty(AccessLevel.GameMaster, readOnly: true)]
         public DateTime Created { get; set; } = Core.Now;
 
-        [CommandProperty(AccessLevel.GameMaster)]
-        DateTime ISerializable.LastSerialized { get; set; } = Core.Now;
-
         public Serial Serial { get; set; }
 
         [AfterDeserialization(false)]