Code review comment for ~sylvain-pineau/checkbox-ng:tp-export

I consider a bad design making the core of checkbox (JobRunner) aware of the TP export functionality and hardcoding a special case for graphics cards. If having specialised JobRunner is the best solution for the problem, let's do just that, by creating FakeJobRunner that overrides necessary parts. It could also help with the problem of propagating tp_export arg (which I would prefer renamed to exported_tp_name, tp_export misled me, but that's subjective).

I know this code does the job, but for me it has a "dirty hack" feel and voids abstractions that are already in place.