Terms and conditions refactoring

Feature Request

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

Terms and conditions (CGV in french) must be specific for every organization. This means that we can't have a global one for the whole platform.

Describe the solution you'd like

Terms and conditions will be included in the contract definition provided by the organization.
There is no more need to accept them in the sale tunnel, they will be signed in the contract (remove this part).
There is no more need to store in the order model if the user accept them (remove it from the model).
There is no more need to store them in the site model in joanie and in richie.
There is no more need to inject them dynamically in the contract, they will be already present.