Reuse of the variable paid_modes was causing the code to follow an
incorrect path. Changed the filtering version of the variable to
paid_modes_only. Had to keep both variables temporarily until I can fix
plugin code that uses this API.
The Demographics CTA is used to ask users to respond to the optional
questions. This API and model support the API being dismissed by the
user so they are not bothered by it.
Make demographics collection banner on dashboard use new demographics
API which checks enterprise as well. Also expose serialization of
CourseEnrollments.
