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.h

@@ -27,6 +27,8 @@ public:
     bool has_frame() const { return m_has_frame; }
     void set_has_frame(bool has_frame) { m_has_frame = has_frame; }
 
+    virtual Optional<UISize> calculated_preferred_size() const override;
+
 protected:
     explicit Toolbar(Gfx::Orientation = Gfx::Orientation::Horizontal, int button_size = 16);