Fix KXmlGUI toolbars; and Konsole MainWindow size

Call setupGUI(), which will call createGUI (since we set the
KXmlGuiWindow::Create flag), omit the StatusBar flag since we don't have a
statusbar and don't want the "Show StatusBar" menu action.

TabbedViewContainer::sizeHint() calculates an optimum size for itself,
including the sizes of its child widgets; added in efb621d0 by
Mariusz Glebocki; following the code:
MainWindow creates a ViewManager
ViewManager creates a TabbedViewContainer and then a TerminalDisplay

which means that the first time TabbedViewContainer::sizeHint() is called
the TerminalDisplay widget size is 0, then TabbedViewContainer::sizeHint()
would return 0.

Which is why calling resize() in MainWindow was delayed to the showEvent(),
(and even delayed more by a QTimer::singleShot() call in Application),
at which point all the child widgets have been created and
MainWindow::sizeHint() (which logically takes into account the sizeHint()
of its child widgets) would return a sensible size.

CCBUG: 430036
CCBUG: 439339
BUG: 436471