Add search_after for better pagination of Episerver Find results

Hi

I noticed recently that ElasticSearch supports a search_after parameter to allow more consistent pagination of query results:

https://www.elastic.co/guide/en/elasticsearch/reference/6.8/search-request-search-after.html

This effectively works by asking for a page worth of sorted results that come after a unique id (tiebreaker). This could be a page content ID in the case of Episerver.

This approach is more reliable that simply asking for a page worth of sorted results that come after some date & time field - because two documents can have the same date & time, which can result in duplicates appearing at the end and beginning of subsequent pages of results.

Can you please add this search_after option to the EpiServer Find client API? 

Thanks

Cameron W