Add a pagination api

[magopian]

This might not be easy: pagination uses continuation token headers. Need to think about what the dream api would look like, and see how usable and feasible it is.

[magopian]

@n1k0 and @Natim have implemented that quite some time ago: https://package.elm-lang.org/packages/Kinto/elm-kinto/latest/Kinto#Pager