Introduce Prev/Next pagination to branches
What does this MR do?
Changes pagination controls from:
To:
It's the next step to improving the performance of Branches page: #211710 (closed).
Technical reason behind the UI change
Gitaly provides page-token pagination for branches instead of offset pagination. That means that we can't easily access a particular page of the branches list without fetching all branches from Gitaly and iterate them manually. However, page-token pagination allows us to retrieve next bunch of branches. We can use it in order to implement prev-next pagination which should work more performant.