Inconsistent handling of string vertex/edge ids collections in DSE Graph steps

The string formatting for vertices with user-defined vertex ids has changed. Invoking toString on a user-defined vertex id containing a text property, or on an edge id that is incident upon a vertex with a user-defined vertex id now returns a value that double-quotes that text property value and escapes the value's internal double-quotes. This change avoids cases where the old format could lead to irresolvable parsing ambiguity. For example, examine the input value and returned value for the following graph statements:

gremlin> graph.addVertex(T.label, "v", "p", "a\"b")
==>v[{~label=v, p="a""b"}]
gremlin> g.V().id().toList()
==>{~label=v, p="a""b"}
gremlin> g.V().id().next().toString()
==>{~label=v, p="a""b"}
gremlin> g.V().toList()
==>v[{~label=v, p="a""b"}]