Added bot_perm support to medusa system

src/Nadeko.Medusa/Attributes/bot_permAttribute.cs

@@ -0,0 +1,23 @@
+using Discord;
+
+namespace Nadeko.Snake;
+
+[AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
+public sealed class bot_permAttribute : MedusaPermAttribute
+{
+    public GuildPermission? GuildPerm { get; }
+    public ChannelPermission? ChannelPerm { get; }
+
+
+    public bot_permAttribute(GuildPermission perm)
+    {
+        GuildPerm = perm;
+        ChannelPerm = null;
+    }
+
+    public bot_permAttribute(ChannelPermission perm)
+    {
+        ChannelPerm = perm;
+        GuildPerm = null;
+    }
+}