fix: Fixes codegenned spawners and adds RunUO spawner import support (#1682)

> [!IMPORTANT]  
> This code change includes important fixes for all spawners after they were converted to codegen!

> [!NOTE] 
> **Developer Note**
> Usage/Description/Aliases attributes were moved to the core so they can be used by the command registration system.

### Summary
- **Fixes spawners not registering their spawns on world load**
- Changes `[GenerateSpawners` to `[ImportSpawners`
- Removes `ConvertPremiumSpawners`
- Adds Premium spawner import support to `[ImportSpawners`
- Adds RunUO XML import support: https://github.com/ruaduck/xmlspawner/blob/ServUOMaster/XmlSpawner/XmlSpawner%20Core/SpawnerExporter.cs
- Fixed an issue where not manually registering an alias meant it wasn't available as a command

Projects/UOContent/Engines/Spawners/SpawnerEntry.cs

@@ -76,14 +76,20 @@ public partial class SpawnerEntry
 
             if (e != null)
             {
-                e.Spawner = _parent;
-
                 Spawned.Add(e);
-                _parent.Spawned.TryAdd(e, this);
             }
         }
     }
 
+    [AfterDeserialization]
+    private void AfterDeserialization()
+    {
+        foreach (var e in Spawned)
+        {
+            e.Spawner = _parent;
+        }
+    }
+
     [JsonIgnore]
     public EntryFlags Valid { get; set; }
 
@@ -99,6 +105,7 @@ public partial class SpawnerEntry
             if (parent.OnDefragSpawn(spawned, false))
             {
                 Spawned.RemoveAt(i--);
+                _parent.MarkDirty();
             }
         }
     }