restore panel when screen geometry changes

the panel size and position is saved per-screen resolution
so at different resolutions (or different screens) the panel always goes
back where it was with the size it had.
this should give a more deterministic behavior to the panel
when resizing the screen (like virualbox) or docking to
an external docking styation

BUG:368741
reviewed-by: David Edmundson <david@davidedmundson.co.uk>

shell/panelview.cpp

@@ -645,8 +645,7 @@ void PanelView::moveEvent(QMoveEvent *ev)
 
 void PanelView::integrateScreen()
 {
-    connect(m_screenToFollow, SIGNAL(geometryChanged(QRect)),
-            this, SLOT(positionPanel()));
+    connect(m_screenToFollow, &QScreen::geometryChanged, this, &PanelView::restore);
     themeChanged();
     KWindowSystem::setOnAllDesktops(winId(), true);
     KWindowSystem::setType(winId(), NET::Dock);