Executing construct queries in streaming and sorted ways

[Aklakan]

In the code there are transformations for 'client-side' construct query execution as well as construct-to-lateral transformers.
The lateral transformation effectively pushes the construct template into the WHERE part which effectively allows for expressing sort conditions of the produced triples in SPARQL.

RPT/integrate needs to expose the features in the CLI:

• Add option for streaming construct (construct-to-lateral with optional distinct/reduced operation). E.g. --construct-streaming[=n] where the value is the window size for reducing duplicated triples; with absent=distinct, 0=no duplicate removal.
• Add convenience option to implicitly sort all construct queries (construct-to-lateral with ORDER BY ?s ?p ?o ?g for nquads)