IAV-888 : enhance subscription promotions management
- Updated SubscriptionsView to integrate promo codes handling, including fetching, creating, and toggling promo codes.
- Modified promotion modal to support viewing and creating promo codes.
- Added new types and interfaces for promo codes in credit-service.types.ts and subscription.ts.
- Introduced a new ConfirmationModal component for user confirmations.
- Created a Yup validation schema for creating promotions, ensuring robust input validation.
Closes IAV-888