fix(wm): socket cleanup on exit

This commit ensures that Shutdown signals will be sent to subscriber
sockets and that "komorebi.sock" will be cleaned up on exit.

Alongside these changes, komorebi_client::send_message no longer retries
so that integrators can receive feedback via io::Result errors when
komorebi is not running.

komorebi/src/lib.rs

@@ -163,7 +163,7 @@ lazy_static! {
     ]));
     static ref SUBSCRIPTION_PIPES: Arc<Mutex<HashMap<String, File>>> =
         Arc::new(Mutex::new(HashMap::new()));
-    static ref SUBSCRIPTION_SOCKETS: Arc<Mutex<HashMap<String, PathBuf>>> =
+    pub static ref SUBSCRIPTION_SOCKETS: Arc<Mutex<HashMap<String, PathBuf>>> =
         Arc::new(Mutex::new(HashMap::new()));
     static ref TCP_CONNECTIONS: Arc<Mutex<HashMap<String, TcpStream>>> =
         Arc::new(Mutex::new(HashMap::new()));