fix: Optimizes OPL using string interpolation (#1041)

## Breaking Changes (New API)
ObjectPropertyList supports the following API:
```cs
list.Add(500000);
list.Add(500001, stringArgument);
list.Add("Some text");
list.Add($"Some text with {argument}");
list.Add(500002, $"{arg1}\t{arg2}");
```

## Notes
1. All API uses that require a formatter like this:
    ```cs
    list.Add(500002, "{0}\t{1}", arg1, arg2);
    ```
    Should be changed to use string interpolation, for example:
    ```cs
    list.Add(500002, $"{arg1}\t{arg2}");
    ```
2. The following paradigm should no longer be used:
    ```cs
    list.Add(1061170, prop.ToString()); // strength requirement ~1_val~
    ```
    The new string interpolation API will avoid having to convert the argument to a string before writing it to the packet. Instead use the following:
    ```cs
    list.Add(1061170, $"{prop}"); // strength requirement ~1_val~
    ```

### Benchmarks
```cs
|                         Method |     Mean |   Error |  StdDev |  Gen 0 | Allocated |
|------------------------------- |---------:|--------:|--------:|-------:|----------:|
|                BenchmarkOldOPL | 241.0 ns | 0.56 ns | 0.47 ns | 0.0105 |      88 B |
| BenchmarkStringInterpolatedOPL | 199.9 ns | 2.44 ns | 2.39 ns |      - |         - |
```

### Changes
- [X] Removes crash in STArray.Return when array is null.
- [X] Fixes NPE in OPL when entity is null. Serial in packet will be 0 when entity is null.
- [X] Fixes NPE in AosAttributes when Parent is null.
- [X] Changes OPL to use string interpolation.
- [X] Introduces `IPropertyList` to allow extending PropertyList for other uses.

Projects/Server/Items/Container.cs

@@ -755,7 +755,7 @@ namespace Server.Items
 
         public virtual void SendContentTo(NetState state) => state.SendContainerContent(state.Mobile, this);
 
-        public override void GetProperties(ObjectPropertyList list)
+        public override void GetProperties(IPropertyList list)
         {
             base.GetProperties(list);
 
@@ -767,21 +767,14 @@ namespace Server.Items
                     {
                         list.Add(
                             1073841, // Contents: ~1_COUNT~/~2_MAXCOUNT~ items, ~3_WEIGHT~ stones
-                            "{0}\t{1}\t{2}",
-                            TotalItems,
-                            MaxItems,
-                            TotalWeight
+                            $"{TotalItems}\t{MaxItems}\t{TotalWeight}"
                         );
                     }
                     else
                     {
                         list.Add(
                             1072241, // Contents: ~1_COUNT~/~2_MAXCOUNT~ items, ~3_WEIGHT~/~4_MAXWEIGHT~ stones
-                            "{0}\t{1}\t{2}\t{3}",
-                            TotalItems,
-                            MaxItems,
-                            TotalWeight,
-                            MaxWeight
+                            $"{TotalItems}\t{MaxItems}\t{TotalWeight}\t{MaxWeight}"
                         );
                     }
 
@@ -790,7 +783,7 @@ namespace Server.Items
                 else
                 {
                     // ~1_COUNT~ items, ~2_WEIGHT~ stones
-                    list.Add(1050044, "{0}\t{1}", TotalItems, TotalWeight);
+                    list.Add(1050044, $"{TotalItems}\t{TotalWeight}");
                 }
             }
         }