gitlab: Iterate over projects by id instead of offset based pagination (#404)
There is a limit for offset based pagination on the projects API. One
option is to use keyset's but go-gitlab has no support for it. Another
related approach is to iterate over project ids. For this we are going
to:
* Order by 'id'
* Sort in ascending order
* Use ID After to move forward until there are no ids
This helps to iterate the number of projects on a large(r) instance
of GitLab.