investigate query results caching for paging SPARQL query results in AllegroGraph

[alexskr]

AllegroGraph v8 introduced query caching feature which can be beneficial with paging sparql queries.
https://franz.com/agraph/support/documentation/8.0.1/sparql-reference.html#query-option.allowCachingResults
We need to evaluate it and implement if it speeds things up.

[alexskr]

implemented in 1707d38