Add a new qemuMonitorJSONGetObjectListPaths() method to support invocation
of the 'qom-list' JSON monitor command with a provided path.

NOTE: The ListPath structures and API's are added only for the
      purpose of the qemumonitorjsontest

The returned list of paired data fields of "name" and "type" that can
be used to peruse QOM configuration data and eventually utilize for the
balloon statistics.

The test does a "{"execute":"qom-list", "arguments": { "path": "/"}}" which
returns "{"return": [{"name": "machine", "type": "child<container>"},
{"name": "type", "type": "string"}]}" resulting in a return of an array
of 2 elements with [0].name="machine", [0].type="child<container>".  The [1]
entry appears to be a header that could be used some day via a command such
as "virsh qemuobject --list" to format output.