Stream g.V(v).outE() results

See https://lists.lfaidata.foundation/g/janusgraph-users/topic/88677270#6380

g.E().hasNext() is fast, and that’s because the results are streamed. On the other hand, g.V(v0).outE().hasNext() is slow if vertex v0 has a huge amount of incident edges, and that’s because the results, in this case, are not streamed. It definitely needs some investigation, but usually, it’s not a big problem because people don’t expect a large number of incident edges attached to a node.

Start with the linked janusgraph-users discussion, then compare the g.E().hasNext() and g.V(v).outE().hasNext() traversal paths. Investigate why incident-edge results are not streamed; done means g.V(v).outE() can begin returning results without waiting for all incident edges to be processed.

Written by the indexing model from the issue text.