fix: Cleans up entity persistence. Generalizes Mobiles/Items/Guilds (#1528)

### Summary
- [X] Fixed a bug where entity persistence was serialized out of order, causing world corruption.
- [X] Fixed LastSerialized not being utilized properly and dangling references still becoming an issue.
- [X] Added a new `GenericEntityPersistence<T>` type to encapsulate `ISerializable` serialization.
- [X] Removing the custom logic and moved Items, Mobiles, Guilds, and Accounts  to GenericEntityPersistence.
- [X] Changed serialization to use the singleton pattern to reduce calling methods from stored variables.

Projects/UOContent/Mobiles/BaseCreature.cs

@@ -1288,7 +1288,7 @@ namespace Server.Mobiles
                 return false;
             }
 
-            if ((m as PlayerMobile)?.GetVirtues()?.HonorActive == true)
+            if (VirtueSystem.GetVirtues(m as PlayerMobile)?.HonorActive == true)
             {
                 return false;
             }