Support Gremlin multi-label vertexes

**Community Note**
* Please use a 👍 reaction to provide a +1/vote. This helps the community and maintainers prioritize this request.
* If you are interested in working on this issue or have submitted a pull request, please leave a comment.

**Is your feature request related to a problem? Please describe.**

Per their [docs](https://docs.aws.amazon.com/neptune/latest/userguide/get-started-graph-gremlin.html), Neptune supports use of multiple labels for a single vertex in Gremlin data, via the `::` syntax.

The Gremlin graph visualizer does not currently recognize or provide any special processing for multi-labels included in query results.

**Describe the solution you'd like**

The Gremlin visualizer options `--display-property` and `--group-by-property` should be able to factor in multi-label vertexes when matching on a single label value.

For example, if a `%%gremlin` query returns the multi-label vertex:
```
{: '0', : 'Label1::Label2::Label3', 'name': 'a_vertex'}
```
Users should be able to pass the following to `--display-property`:
```
my_node_labels = ‘{“Label1”:“name”}’`
```
And get "a_vertex" as the displayed value on the same vertex in the visualized graph.