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/AI/BaseAI.cs

@@ -2702,7 +2702,7 @@ public abstract class BaseAI
             }
 
             // Ignore players with activated honor
-            if (m_Mobile.Combatant != m && pm?.GetVirtues()?.HonorActive == true)
+            if (m_Mobile.Combatant != m && VirtueSystem.GetVirtues(pm)?.HonorActive == true)
             {
                 continue;
             }