Adds a course_ids api that can filter by user role, since the courses
api could not perform well enough for this, and returned much more
data than we need.
Additionally, adds a LazyPageNumberPagination to provide more accurate
counts in the pagination response when using LazySequence with the
queryset.
BOM-897
BOM-1228
The api is already not very performant and trying to limit it to only
show courses where you are staff causes the code to iterate over almost
all the courses and times out before it returns any results to the user.
The plan is to build a different api for the thing we need that will
just provide the course IDs for courses where you are staff and sholud
be much faster.
