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/Server/Json/JsonConfig.cs

@@ -49,6 +49,7 @@ public static class JsonConfig
         options.Converters.Add(new IPEndPointConverterFactory());
         options.Converters.Add(new TypeConverterFactory());
         options.Converters.Add(new WorldLocationConverterFactory());
+        options.Converters.Add(new TextDefinitionConverterFactory());
 
         for (var i = 0; i < converters.Length; i++)
         {