wicket-dbg "run" behavior confusing - need better state management

This is a bug currently affecting the not yet merged wicket-dbg in https://github.com/oxidecomputer/omicron/pull/2682.

wicket-dbg allows running playback of a recording with the run command. Playback can be resumed with the resume command. The rationale for a separate command was to allow run to be entered again and start from the beginning. However, it appears that run will actually start over, but not all the state is reset leading to anomalous behavior. It also isn't clear that the resume command should even exist. We already have reset for manually going back to the beginning.

Suggested fix is to remove the resume command, ensure that reset actually resets all state to default, and then allow run to resume from the current event when playback is not already running.