PixelPaint: Support using a bitmap as a tool's cursor

Author: https://github.com/mrkct
Commit: 0f24678eaf
Pull-request: https://github.com/SerenityOS/serenity/pull/10381
Reviewed-by: https://github.com/BenWiederhake ✅
Reviewed-by: https://github.com/TobyAsE
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/kleinesfilmroellchen

Userland/Applications/PixelPaint/Tools/LineTool.h

@@ -23,7 +23,7 @@ public:
     virtual void on_second_paint(Layer const*, GUI::PaintEvent&) override;
     virtual void on_keydown(GUI::KeyEvent&) override;
     virtual GUI::Widget* get_properties_widget() override;
-    virtual Gfx::StandardCursor cursor() override { return Gfx::StandardCursor::Crosshair; }
+    virtual Variant<Gfx::StandardCursor, NonnullRefPtr<Gfx::Bitmap>> cursor() override { return Gfx::StandardCursor::Crosshair; }
 
 private:
     RefPtr<GUI::Widget> m_properties_widget;