AppletPopup window type should accept focus.

AppletPopup window type should accept focus, behaving like other window types like
Dock. At the moment it is instead behaving like notification, which seems wrong.
This should also fix a failing unit test.

src/xdgshellwindow.cpp

@@ -1065,7 +1065,6 @@ bool XdgToplevelWindow::acceptsFocus() const
         switch (m_plasmaShellSurface->role()) {
         case PlasmaShellSurfaceInterface::Role::Notification:
         case PlasmaShellSurfaceInterface::Role::CriticalNotification:
-        case PlasmaShellSurfaceInterface::Role::AppletPopup:
             return m_plasmaShellSurface->panelTakesFocus();
         default:
             break;