Switch to an object based approach for Pilots

[Ichmed]

Right now each pilot runs by reading a config file, creating an environment and then executing that environment.

This is basically already a constructor and method call approach just abstracted away needlessly. By creating a struct

struct PodmanPilot<'a> {
  config: Config<'a>,
  program_name: String,
  ...
}

impl<'a> Pilot for PodmanPilot<'a> {
  ...
}

And implementing the current create and start functions on that struct we gain the following benefits:

• Using self instead of config() is more readable
• No need for lazy static etc.
• The pilot can easily mutate itself where needed
• It is clear at first glance that each config defines a single pilot
• Lifetimes become easier since it is not possible to call the methods without a Pilot struct
• People who want to implement their own Pilots can use the Pilot trait as orientation.

The following things would be possible even though i don't see any need for them:

• Have multiple Pilots in one runtime
• Create code that's generic over a Pilot trait
• Have Vec<dyn Pilot> or similar structs that can even handle pilots of different types

The new main method would look something like this:

  ...
  let config = config_for_name(&program_name);
  PodmanPilot::from_config(config)?.create()?.run()
}

By implementing Drop on the Pilot struct, cleanup code can also be made easier.