"Run previous spec" command

## What

Allows re-running the last spec, regardless of the current active editor. Eliminates need to switch back to spec file to re-run last spec.

## Testing

1. Run specs normally, either using the "run-file" or "run-line" command.
2. Switch to a different editor tab
3. Run the "run-previous" command (Ctrl+Alt+r, p)