feat: Add enhanced PIX payment functionality with custom UI

- Implemented `doPixPaymentWithUI` function to process PIX payments with customizable UI options.
- Added UI messages, behavior, and styling for a better user experience during PIX transactions.
- Integrated the new PIX payment method into the App component, allowing users to initiate payments with a dedicated button.
- Updated styles for the PIX payment button and text to match the new design.

Author: mCodex