Medusa System Added

Read about the medusa system [here](https://nadekobot.readthedocs.io/en/latest/medusa/creating-a-medusa/)

src/NadekoBot/Common/Medusa/Config/MedusaConfigService.cs

@@ -0,0 +1,43 @@
+using NadekoBot.Common.Configs;
+
+namespace Nadeko.Medusa;
+
+public sealed class MedusaConfigService : ConfigServiceBase<MedusaConfig>, IMedusaConfigService
+{
+    private const string FILE_PATH = "data/medusae/medusa.yml";
+    private static readonly TypedKey<MedusaConfig> _changeKey = new("config.medusa.updated");
+
+    public override string Name
+        => "medusa";
+
+    public MedusaConfigService(
+        IConfigSeria serializer,
+        IPubSub pubSub)
+        : base(FILE_PATH, serializer, pubSub, _changeKey)
+    {   
+    }
+
+    public IReadOnlyCollection<string> GetLoadedMedusae()
+        => Data.Loaded.ToList();
+
+    public void AddLoadedMedusa(string name)
+    {
+        name = name.Trim().ToLowerInvariant();
+        
+        ModifyConfig(conf =>
+        {
+            if(!conf.Loaded.Contains(name))
+                conf.Loaded.Add(name);
+        });
+    }
+    
+    public void RemoveLoadedMedusa(string name)
+    {
+        name = name.Trim().ToLowerInvariant();
+        
+        ModifyConfig(conf =>
+        {
+            conf.Loaded.Remove(name);
+        });
+    }
+}