Add checkbox so learner can be enrolled directly from the partner

[igobranco]

We need a similar feature of the edx.org.
That allows the learner to accept to receive information from the partner related to the course.

On Richie API https://github.com/fccn/edx-platform/blob/452b82e68b63bef8b4ff7a5027cde0b38961df6b/openedx/core/djangoapps/enrollments/views.py#L503C17-L503C29

Send the email_opt_in Open edX Enrollment API parameter with the value of the new check.
https://github.com/openfun/richie/blob/master/src/frontend/js/api/lms/openedx-hawthorn.ts#L109-L113