sd: sidebar: force to set the id of the LayoutMenu control

Otherwise, the function std::unique_ptr<UIObject>
WindowUIObject::get_child(const OUString& rID)
will not find the control with the rID.

Change-Id: Ie571eb351bb0c59654f577cef1961247273d7608
Reviewed-on: https://gerrit.libreoffice.org/81345
Tested-by: Jenkins
Reviewed-by: Henry Castro <hcastro@collabora.com>
diff --git a/sd/source/ui/sidebar/LayoutMenu.cxx b/sd/source/ui/sidebar/LayoutMenu.cxx
index ab58af5..bacfa1c5 100644
--- a/sd/source/ui/sidebar/LayoutMenu.cxx
+++ b/sd/source/ui/sidebar/LayoutMenu.cxx
@@ -135,6 +135,7 @@ LayoutMenu::LayoutMenu (
      mxSidebar(rxSidebar),
      mbIsDisposed(false)
{
    set_id("sd::LayoutMenu");
    implConstruct( *mrBase.GetDocument()->GetDocSh() );
    SAL_INFO("sd.ui", "created LayoutMenu at " << this);