feat: restrict commands from being used in DMs

- Added `allow_in_dm: false` to various moderation, utility, and role management commands to prevent their usage in direct messages.
- Updated the message event handler to check for the `allow_in_dm` flag and respond appropriately when a DM command is attempted.

src/commands/infos/banner.rs

@@ -71,6 +71,7 @@ impl crate::commands::command_contract::CommandSpec for BannerCommand {
             description: "Affiche la banniere de profil dun utilisateur cible ou de lauteur.",
             examples: &["+banner", "+br", "+help banner"],
             default_aliases: &["bnr"],
+            allow_in_dm: true,
             default_permission: 0,
         }
     }