Paginate all API endpoints that return an array?

I have a few questions about pagination in the API:

1. Do we want all API endpoints that return an array of resources to be paginated? I would say yes to that
2. If yes, it could break current usage of the API, e.g. you can currently get all the commits of a MR in one call but you'd have to make several calls if we paginate this resource
3. Broader question: how do we currently handle such changes in the API?

/cc @dzaporozhets @DouweM @rspeicher