Purchase tunnel : enable the insertion of discount codes

[cuchulainn-fun]

Feature Request

Is your feature request related to a problem or unsupported use case? Please describe.

There is no input field for discount codes on the platform's user interface, particularly in the payment section. BtoC pattern

Describe the solution you'd like
The idea is to be able to enter the code:

either before subscribing, particularly in the training summary window (the red button)

However, this window already contains dynamic text relating to the appearance of a tick linked to the start date of the training course. This tick appears if the user subscribes less than 14 days before the start date of the training course

or when the user goes to enter their credit card details, but it seems that this window is linked to Payzen.