Create tests to validate embedded commands

Skaffold shows command lines to help users accomplish certain tasks.

For example, we ask the user to run `skaffold survey` to take the HaTS survey:
https://github.com/GoogleContainerTools/skaffold/blob/8d0a32f6fd7a6a361e9143567ed406750d633c0a/pkg/skaffold/survey/config.go#L68-L72

We also include Skaffold command lines in our examples

https://github.com/GoogleContainerTools/skaffold/blob/8d0a32f6fd7a6a361e9143567ed406750d633c0a/cmd/skaffold/app/cmd/run.go#L36-L37

But we sometimes get these wrong, or changes introduce errors: the `skaffold survey -id` example should actually use `--id`.

We should be able to write tests to validate these commands with the cobra args infrastructure.