Cookiecutter - update to support a Scaleway CDN infrastructure (as done on `fun-richie-site-factory`)

[wilbrdt]

Feature Request

Is your feature request related to a problem or unsupported use case? Please describe.
As our plan to migrate away from AWS, the fun-richie-site-factory has been modified to support setting up a CDN infrastructure on Scaleway, using Scaleway S3 and Edge services. All site settings have all been adapted to work with this new setup. However, the current cookie cutter does not support these changes, making it harder for others to adopt the new infra.

Describe the solution you'd like
The cookie cutter should be updated to reflect the recent changes from fun-richie-site-factory. The relevant PRs are: openfun/fun-richie-site-factory#276 and openfun/fun-richie-site-factory#278