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/administration/unowner.rs

@@ -81,6 +81,7 @@ impl crate::commands::command_contract::CommandSpec for UnownerCommand {
             description: "Retire un utilisateur de la liste des owners supplementaires du bot.",
             examples: &["+unowner", "+ur", "+help unowner"],
             default_aliases: &["uow"],
+            allow_in_dm: false,
             default_permission: 9,
         }
     }