LibGUI: Use new layout system for basic widgets

Author: https://github.com/frhun
Commit: 19fac58e49
Pull-request: https://github.com/SerenityOS/serenity/pull/14261
Reviewed-by: https://github.com/AtkinsSJ ✅
Reviewed-by: https://github.com/MacDue
Reviewed-by: https://github.com/mjz19910

Userland/Libraries/LibGUI/Toolbar.cpp

@@ -133,4 +133,13 @@ void Toolbar::paint_event(PaintEvent& event)
     painter.fill_rect(event.rect(), palette().button());
 }
 
+Optional<UISize> Toolbar::calculated_preferred_size() const
+{
+    if (m_orientation == Gfx::Orientation::Horizontal)
+        return { { SpecialDimension::Grow, SpecialDimension::Fit } };
+    else
+        return { { SpecialDimension::Fit, SpecialDimension::Grow } };
+    VERIFY_NOT_REACHED();
+}
+
 }