Add CommandAction function

[andrzejressel]

When you just want to set Action when using Command

[jawher]

Thanks @jereksel for your contribution !

To keep the surface area as small as possible, and to avoid code duplication, what do you think about implementing this differently: instead of exposing a CommandAction function, provide instead a (top-level) function which takes the action function and returns one suitable for a command initializer ? Concretely, it would look like this:

app.Command("list", "list all configs", cli.ActionCommand(func()) {
  // ...
}))

[andrzejressel]

Sure, sound good to me

[jawher]

@jereksel Thanks for the quick fix. One last remark to handle and it should be good for mege 👍

[jawher]

@jereksel Thank you for your contribution !