Refactor GitHub API service objects to respect potential pagination

[hpjaj]

Background

Background is the TODO here:

TODO: Maxing the page size at 100 is standing in place for implementing
a pagination solution. At this point, as we will have daily cron jobs
for these endpoints, it is unrealistic to think that any user would have
more than 100 items returned in any of these endpoints, in a given day.
As such, pagination is not yet required.

Definition of Done

• When necessary, implement a pagination solution that leverages GitHub's pagination feedback