Implement scrolling search in `data.elasticsearch` data source

What was changed

searchWithScroll and searchWithScrollConfigurable functions were added:
- the functions implement Elasticsearch scroll search logic (with searchWithScrollConfigurable accepting a step size as input param, for testing)
- the data source will use a simple search if the requested size is <= maxSimpleSearchResultsSize (10000), and use scrolling search otherwise
2 integration tests added to verify that the data source makes a correct selection with the large size, and to verify that the multiple-search-steps logic works
small naming fix for Elastic cases data source