Change interest notification to link to course edition project page

When you join the interest list of a particular project, if the proposers of that project change something in its description, students on the interest list will receive a notification. However, the link to the project shown in the notification is slightly different: instead of it being of the form https://projectforum.tudelft.nl/course_editions/[COURSE_NUMBER]/generic_projects/[PROJECT_NUMBER], it has the form of https://projectforum.tudelft.nl/projects/[PROJECT_NUMBER]

Write a migration to migrate existing notifications.