feat: add four skeletons of commands

src/command/mod.rs

@@ -9,6 +9,10 @@ use twilight_model::application::{
     command::Command, interaction::application_command::CommandData,
 };
 
+mod join;
+mod leave;
+mod opt_out;
+
 #[derive(Debug, Clone)]
 pub struct State {}
 
@@ -24,7 +28,11 @@ where
 }
 
 pub fn all() -> Vec<(&'static Command, BoxedHandler)> {
-    vec![]
+    vec![
+        (&join::COMMAND, box_handler(join::handle)),
+        (&leave::COMMAND, box_handler(leave::handle)),
+        (&opt_out::COMMAND, box_handler(opt_out::handle)),
+    ]
 }
 
 #[derive(Default)]