add an option to add triples directly to a target graph (skipping the temp graph)

[nvdk]

Currently, when uploading large datasets triples are first inserted into a temp graph and then moved to the destination graph with a graph operation. The main benefit is that this allows rolling back / cancelling the upload if it fails at some point before the graph operation.

Since mu-auth doesn't support graph operations I'd suggest we add a switch that replaces the graph operation with a delete/insert query. The default should remain the graph operation for backwards compatibility