Organized some db models into folders

src/Nadeko.Bot.Db/Models/punish/MutedUserId.cs

@@ -0,0 +1,13 @@
+#nullable disable
+namespace NadekoBot.Services.Database.Models;
+
+public class MutedUserId : DbEntity
+{
+    public ulong UserId { get; set; }
+
+    public override int GetHashCode()
+        => UserId.GetHashCode();
+
+    public override bool Equals(object obj)
+        => obj is MutedUserId mui ? mui.UserId == UserId : false;
+}