Depends on D85705.
The previous diff left the Dump command unimplemented, so I'm implementing it.
As we add more stuff into the intel-pt plugin, we'll dump more information. For now, showing the current settings seems okay.
The dump command will print the information of the currently selected target.
This diff is also important because it introduces Target as the owner of the Trace object. If a trace corresponds
to multiple targets, then all of then will share the same Trace.