Option to prevent splitting graphs in the SPARQL constuct component

[rorlic]

Currently, the behavior of the SPARQL constuct LDIO component is: check if resulting triples contains a named graph and,
if one or more named graphs is found, split the triples into the named graph, adding the default graph to each named graph before pushing it into the rest of the pipeline, else send the triples as-is in the rest of the pipeline.

This behavior is fine for splitting a message into multiple messages for individual handling. However, sometimes you actually want to keep the named graph(s) as a whole and send it further downstream, e.g. when creating a data client pipeline outputtng to a graphdb you want to keep the named graph so that you can replace the named graph as a whole.

So, please add an option to prevent splitting by named graph keeping the current behavior as the default.