fix: fix wayland client dispatch loop

In previous commit d63a6b we dispatch wayland events purely inside the
QSocketNotifier. This will cause server events that is send before the
notifier created is not being dispatched, which is not what we want and
will cause severe issue in the current interaction model of ddm &
treeland, as treeland will send an event immediately after ddm is
connected. Fix it by dispatch once before create notifier.

Author: calsys456

src/daemon/TreelandConnector.cpp

@@ -205,6 +205,8 @@ void TreelandConnector::connect(QString socketPath) {
 
     wl_display_roundtrip(m_display);
 
+    wl_display_dispatch(m_display);
+    wl_display_flush(m_display);
     m_notifier = new QSocketNotifier(wl_display_get_fd(m_display), QSocketNotifier::Read);
     QObject::connect(m_notifier, &QSocketNotifier::activated, this, [this] {
         if (wl_display_dispatch(m_display) == -1 || wl_display_flush(m_display) == -1) {