SPARQL DESCRIBE query output format should default to a graph format instead of tabular

**Is your feature request related to a problem? Please describe.**
As described in the SPARQL specification, "the DESCRIBE form takes each of the resources identified in a solution, together with any resources directly named by IRI, and assembles a single RDF graph..." (ref: https://www.w3.org/TR/sparql11-query/#describe). For this reason, it is frustrating that the graph notebook returns this data in a tabular format by default.
When I use most SPARQL toolsets, the output format defaults to a graph format like Turtle when running a DESCRIBE query.

**Describe the solution you'd like**
I would like the graph notebook to recognize that a DESCRIBE query is being run and return the data in a graph format instead of tabular format.

**Describe alternatives you've considered**
I likely could write Python code that would send HTTP requests to the Neptune endpoint requesting the specific MIME type, but that would be burdensome on my non-programmer staff.

**Additional context**
.