Improve steering and config

[benedikt-voelkel]

• add something like o2tuner-config to handle inspection and potentially creation and modification of steering configuration, e.g.
  • o2tuner-config make-skeleton to create a skeleton
  • o2tuner-config -c <config.yaml> show --stages to show available stages
  • o2tuner-config -c <config.yaml> add to add a stage to the config
• make configuration and its usage as save as possible, add further checks at runtime before working through the stages
• add a default evaluation stage that can simply be taken by the user without the necessity to implement their own evaluation stage (unless they need special functionality)