LibGUI: Add min_size to Layout

Author: https://github.com/frhun
Commit: b2951a2116
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/BoxLayout.h

@@ -23,6 +23,7 @@ public:
 
     virtual void run(Widget&) override;
     virtual Gfx::IntSize preferred_size() const override;
+    virtual UISize min_size() const override;
 
 protected:
     explicit BoxLayout(Gfx::Orientation);