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/Engines/Player Murder System/PlayerMurderSystem.cs

@@ -8,8 +8,10 @@ using Server.Mobiles;
 
 namespace Server.Engines.PlayerMurderSystem;
 
-public static class PlayerMurderSystem
+public class PlayerMurderSystem : GenericPersistence
 {
+    private static PlayerMurderSystem _playerMurderPersistence;
+
     private static readonly ILogger logger = LogFactory.GetLogger(typeof(PlayerMurderSystem));
 
     // All of the players with murders
@@ -28,10 +30,10 @@ public static class PlayerMurderSystem
 
     public static void Configure()
     {
-        GenericPersistence.Register("PlayerMurders", Serialize, Deserialize);
-
         _shortTermMurderDuration = ServerConfiguration.GetOrUpdateSetting("murderSystem.shortTermMurderDuration", TimeSpan.FromHours(8));
         _longTermMurderDuration = ServerConfiguration.GetOrUpdateSetting("murderSystem.longTermMurderDuration", TimeSpan.FromHours(40));
+
+        _playerMurderPersistence = new PlayerMurderSystem();
     }
 
     public static void Initialize()
@@ -49,6 +51,10 @@ public static class PlayerMurderSystem
         }
     }
 
+    public PlayerMurderSystem() : base("PlayerMurders", 10)
+    {
+    }
+
     // Only used for migrations!
     public static void MigrateContext(PlayerMobile player, TimeSpan shortTerm, TimeSpan longTerm)
     {
@@ -61,7 +67,7 @@ public static class PlayerMurderSystem
             return;
         }
 
-        var context = player.GetOrCreateMurderContext();
+        var context = GetOrCreateMurderContext(player);
 
         // We make a big assumption that by the time this is called, the Mobile/PlayerMobile info is deserialized
         if (Mobile.MurderMigrations?.TryGetValue(player, out var shortTermMurders) == true)
@@ -100,7 +106,7 @@ public static class PlayerMurderSystem
         }
     }
 
-    private static void Deserialize(IGenericReader reader)
+    public override void Deserialize(IGenericReader reader)
     {
         var version = reader.ReadEncodedInt();
 
@@ -114,7 +120,7 @@ public static class PlayerMurderSystem
         }
     }
 
-    private static void Serialize(IGenericWriter writer)
+    public override void Serialize(IGenericWriter writer)
     {
         writer.WriteEncodedInt(0); // version
 
@@ -126,10 +132,10 @@ public static class PlayerMurderSystem
         }
     }
 
-    public static bool GetMurderContext(this PlayerMobile player, out MurderContext context) =>
+    public static bool GetMurderContext(PlayerMobile player, out MurderContext context) =>
         _murderContexts.TryGetValue(player, out context);
 
-    public static MurderContext GetOrCreateMurderContext(this PlayerMobile player)
+    public static MurderContext GetOrCreateMurderContext(PlayerMobile player)
     {
         ref var context = ref CollectionsMarshal.GetValueRefOrAddDefault(_murderContexts, player, out var exists);
         if (!exists)
@@ -142,14 +148,14 @@ public static class PlayerMurderSystem
 
     public static void ManuallySetShortTermMurders(PlayerMobile player, int shortTermMurders)
     {
-        var context = player.GetOrCreateMurderContext();
+        var context = GetOrCreateMurderContext(player);
         context.ShortTermMurders = shortTermMurders;
         UpdateMurderContext(context);
     }
 
     public static void OnPlayerMurder(PlayerMobile player)
     {
-        var context = player.GetOrCreateMurderContext();
+        var context = GetOrCreateMurderContext(player);
         context.ShortTermMurders++;
         player.Kills++;