Implement operate for badge

#375 in iced-rs/iced_aw — merged 2025-12-26

Added dependency for iced_test (Iced library for testing iced applications in headless mode). I also implemented the fn operate() function on the badge widget, as it was needed to perform iced_test automation testing on the widget.

# unit test pass
cargo test widget::badge

# integration tests pass
cargo test --test badge_integration_tests

References

• RFC #7: Widget Operations
• Iced Test library