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/Attributes.cs

@@ -125,6 +125,30 @@ public class ConstructibleAttribute : Attribute
     public AccessLevel AccessLevel { get; set; }
 }
 
+[AttributeUsage(AttributeTargets.Method)]
+public class UsageAttribute : Attribute
+{
+    public UsageAttribute(string usage) => Usage = usage;
+
+    public string Usage { get; }
+}
+
+[AttributeUsage(AttributeTargets.Method)]
+public class DescriptionAttribute : Attribute
+{
+    public DescriptionAttribute(string description) => Description = description;
+
+    public string Description { get; }
+}
+
+[AttributeUsage(AttributeTargets.Method)]
+public class AliasesAttribute : Attribute
+{
+    public AliasesAttribute(params string[] aliases) => Aliases = aliases;
+
+    public string[] Aliases { get; }
+}
+
 [AttributeUsage(AttributeTargets.Property)]
 public class CommandPropertyAttribute : Attribute
 {