🐛(backend) enrollment search by query string for backoffice django

[jonathanreveille]

For the django backoffice, when we use the search bar, there was an error thrown where it cannot resolve the keyword 'organization' into the fields. The path to obtains the organization field was not set up properly in the search fields of the admin class.

Purpose

To use the search bar on the enrollment view of the django backoffice, we have to set a User first (RequiredUserFilter) and then add the string in the search bar that we want. The options available are : by username, by email, by course title and finally by organization.

Proposal

• [x] Fix search fields of the class Enrollment for the Django admin view.
• [x] Add test for every sort of search fields available for this class

[jbpenrath]

You should add an entry in the CHANGELOG.