Optimade API curser-based pagination
From a slack conversation with Matthew: ES not being a database in the traditional sense, can't deal well with offset-based pagination. Ideally, we would feature cursor-based pagination. I was just too lazy when adapting the curser-based OPT base-classes for ES. The curser-based search is kinda hard to implement since the cursers depend on the search criteria, might need a tie-breaker, etc.