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/Gumps/WhoGump.cs

@@ -43,12 +43,12 @@ namespace Server.Gumps
 
         public static void Configure()
         {
-            CommandSystem.Register("Who", AccessLevel.Counselor, WhoList_OnCommand);
             CommandSystem.Register("WhoList", AccessLevel.Counselor, WhoList_OnCommand);
         }
 
-        [Usage("WhoList [filter]"), Aliases("Who"),
-         Description("Lists all connected clients. Optionally filters results by name.")]
+        [Usage("WhoList [filter]")]
+        [Aliases("Who")]
+        [Description("Lists all connected clients. Optionally filters results by name.")]
         private static void WhoList_OnCommand(CommandEventArgs e)
         {
             e.Mobile.SendGump(new WhoGump(e.Mobile, e.ArgString));