Tech discovery - Discount codes in checkout

For show the feature on checkout:

Enable feature flag: ENABLE_PROMO_CODE_AT_CHECKOUT = 'enablePromoCodeAtCheckout'
After configure sanity:
- https://rbictg.atlassian.net/wiki/spaces/COG/pages/3445949068/Offers#Rulesets
- Systemwide Offers

After that:

To create the promotional codes, we need to access from Voucherify, this vendor is used current by PLK ES in production to create another promo codes on offers page;