Create abstraction over search_after for pagination

[Radiergummi]

Elasticsearch recommends using search_after instead of the scroll API for pagination. Using it requires lots of knowledge about Elasticsearch though, and it's quite cumbersome currently.
We should provide a simple wrapper for this new pagination API.

[chai-masalla]

@Radiergummi Hi

I added PIT mechanism as part of this issue, how can I push it?

[Radiergummi]

Hi @chai-masalla, I'd be very much interested in this!

To add your changes, please follow the contribution guide by GitHub, and I will review and merge the PIT feature. Excited to have this in the library 🙂