Add a destroy app command

[lucarin91]

Describe the request

We could add a new app destroycommand (or a similar name) for stopping and removing all the data of an app.
In particular, we should do a docker-compose down and remove the .cache.

We should also consider adding a destroyed (or a better name) that is the default state of an app if it has not been run yet.
With this additional state, we would then be able to always return a state when listing the apps (right now apps and examples that have not been run, will show up as with no state).

[mirkoCrobu]

@lucarin91, do you think the destroy command should also include image removal, or should we delete just containers, related volumes, and the .cache folder?

[lucarin91]

@lucarin91, do you think the destroy command should also include image removal, or should we delete just containers, related volumes, and the .cache folder?

I would do a docker-compose down and .cache removal in the app folder.